No common name

Larvae found in the colony from April to October. CONSERVATION STATUS Not listed by the IUCN. SIGNIFICANCE TO HUMANS None known. Leptoclinum commune Delia Valle, 1877, Naples Gulf, Italy. Colonial species with small (up to 1.2 in, or 3 cm, in diameter), red, encrusting colonies. Colony contains numerous minute calcareous spicules and feels hard to the touch. Very small zooids are completely embedded in the common test numerous small openings of branchial siphons and several larger cloacal...

Behavior

Little is known about the behavior of tapeworms in the intestine of the host. It seems that most of the tapeworms are permanently attached during their entire life at a certain site of the intestinal wall. However, there are well-documented observations on circadian migrations of Hymenolepis diminuta (Hymenolepididae) from one microhabitat to another in the intestine of rats. This migration depends on the host feeding and digestion. When the gut of the rat is empty, the worms of this species...

Resources Books

Marine Pharmacology. Baltimore Williams and Wilkins, 1969. Fusetani, Nobuhiro, ed. Drugs from the Sea. Basel Karger, 2000. Pietra, Francesco. Biodiversity and Natural Product Diversity. London Pergamon, 2002. Scheuer, Paul J. Chemistry of Marine Natural Products. New York Academic Press, 1973. Faulkner, D. John. Marine Natural Products. Natural Product Reports 19 (2002) 1-48. Newman, David J., Gordon M. Cragg, and Kenneth M. Snader. The Influence of Natural Products upon Drug...

Habitat

The medusae of the Hydrozoa and the siphonophores are mostly planktonic they are seasonal in occurrence and can be present in swarms, transported by the currents. Some medusae and some siphonophores, however, can be benthic. The polyp stages are usually benthic and live attached to the bottom, even though some species can be planktonic, such as the well-known Velella velella. The Hydrozoa occur in all aquatic habitats, from anchia-line caves to deep-sea trenches, from lakes and ponds to rocky...

Reproductive biology

Eggs are about 0.00394 in (100 pm) in diameter and contain numerous yolk droplets. Spermatozoa are simple and typical for marine invertebrate species with external fertilization. Eggs and sperm are released into the water. How spawning is synchronized is not known. In subtropical populations the reproductive period stretches over several months and individuals spawn repeatedly. In temperate areas the reproductive period is shorter. Total, radial cleavage is followed by the formation of a...

Feeding ecology and diet

All scyphozoans feed with tentacles or tentacle-like projections that have millions of microscopic intracellular organelles called nematocysts. Some nematocysts act to Moon jellies (Aurelia aurita). Shedd Aquarium. Photo by Edward G. Lines, Jr. Reproduced by permission.) Moon jellies (Aurelia aurita). Shedd Aquarium. Photo by Edward G. Lines, Jr. Reproduced by permission.) paralyze or kill the prey, whereas others entangle them. Stau-romedusae catch prey by the tentacles and fold the arm inward...

Evolution and systematics

The name Kinorhyncha comes from the Greek words kinema (motion) and rhynchos (proboscis or snout). Kinorhyncha is considered either a class within the phylum As-chelminthes or a separate phylum with close relationships to aschelminth worms. However, the Kinorhyncha was later included as a class in the phylum Cephalorhyncha, established for four classes of Aschelminthes Priapulida, Kinorhyncha, Loricifera, and Nematomorpha. Treated here as a phylum, Kinorhyncha encompasses two orders, five...

Physical characteristics

The animals are bilaterally symmetric with a head, trunk, and tail. They are transparent the internal organs can clearly be seen in living specimens and in specimens that have been well preserved in formalin. The body cavity is filled with fluid that is surrounded by muscles and tough membrane a mul-tilayered epidermis covers the outer layer of the body. The head has a complex musculature that supports the grasping spines or hooks that are the most obvious and recognizable features of this...

Resources

Ophiuroidea) Do Not Support Color Varieties as Sibling Species. Marine Ecology Progress Series 219 (2001) 169-175. Stewart, B. Can a Snake Star Earn Its Keep Feeding and Cleaning Behavior in Astrobrachion constrictum (Farquhar) (Echinodermata Ophiuroidea), a Euryalid Brittle-star Living in Association with the Black Coral, Antipathes fiordensis (Grange, 1990). Journal of Experimental Marine Biology and Ecology 221 (1998) 173-189. Stewart, B., and P. V. Mladenov. Reproductive Periodicity in the...

Salp

Solitary stage has a very thick test, 20 weakly developed muscle bands, two prominent posterior green lateral projections, and can reach up to 13 in (33 cm) in length, making it the largest of all salps. Aggregate stage up to 10 in (25 cm) and five muscle bands. Prominent gut mass is often red-pigmented in both stages. Semi-cosmopolitan in temperate to tropical waters. (Specific distribution map not available.) Commonly found in oceanic surface waters down to 490 ft (150 m). Can be very...

Sea pig

Ascidia pyriformis Rathke, 1806, Bergen, Norway. Solitary species. Red or purple barrel-shaped body, up to 3.9 in (10 cm) in height, attached by the posterior end to hard substratum. Two well-developed siphons are positioned on the anterior end of body and covered by thin spines. Similar, but smaller spines cover the whole test. Arctic North America and north Atlantic coasts of North America Greenland Iceland Spitsbergen, Norway White Sea Barents Sea. Rocky or stony bottoms at depths from 0 to...

Fire coral

Millepora alcicornis Linnaeus, 1758, West Indies. OTHER COMMON NAMES English Sea ginger French Corail de feu German Feuerkorallen. Hydroid colony forms massive, calcareous exoskeletons (coenosteum), forming horn-shaped, upright branches or plates coenosteum with an internal complex network of coenosarcal tubes, covered externally by a thin ectodermal layer, coenosteal surface perforated by pores margins of pores not protruding from surface of coenosteum large gastropores surrounded by smaller...

How to use this book

Grzimek's Animal Life Encyclopedia is an internationally prominent scientific reference compilation, first published in German in the late 1960s, under the editorship of zoologist Bernhard Grzimek (1909-1987). In a cooperative effort between Gale and the American Zoo and Aquarium Association, the series has been completely revised and updated for the first time in over 30 years. Gale expanded the series from 13 to 17 volumes, commissioned new color paintings, and updated the information so as...

Introduction

Symbiosis is an association between two or more different species of organisms. The association may be permanent, the organisms never being separated, or it may be long lasting. Life is complex and often involves a delicate balancing act between hosts and symbionts, in associations that range from parasitism to mutualism. In the long history of life on Earth, symbionts have evolved many protective strategies in their attempts to overcome a host's defenses, including molecular camouflage,...

Migratory behavior

Migration is a second example of communication behavior. Migratory behavior refers to the movement of entire populations. For invertebrates such movement can range from one or two meters to hundreds of meters. Some well known examples of migratory behavior can be found among insects such as the monarch butterfly, Danaus plexippus (Danaidae) and the locust Schistocerca gregaria (Tettigoniidae). During migration, activities such as foraging for food and engaging in mate selection are reduced or...

Organized by taxonomy

The overall structure of this reference work is based on the classification of animals into naturally related groups, a discipline known as taxonomy the science in which various organisms are discovered, identified, described, named, classified, and catalogued. Starting with the simplest life forms, the lower metazoans and lesser deuterostomes, in volume 1, the series progresses through the more complex classes of animals, culminating with the mammals in volumes 12-16. Volume 17 is a...

Distribution

Occurs worldwide from the equator to polar regions at all ocean depths. Latitudinal variation in taxonomic composition is pronounced, even at the level of orders. The shallow-water tropics to warm temperate regions are the most diverse and are dominated by members of the aspidochirote families Holothuriidae and Stichopodidae. The diversity of these families peaks on coral reefs, where 20 species per 2.5 acres (1 hectare) is not uncommon. Dendrochirotes live here as well but become a dominant...

Pea urchin

Among one of the smallest urchins, its tiny oval test measures up to a maximum 0.6 in (1.5 cm) in length. Usually gray-green to bright green in color with very short spines, which give the animal a velvet texture to touch. European coastal waters to a depth of 165 ft (50 m). HABITAT Lives buried in coarse gravel, sandy sediment, and among Zos-teria and maerl beds. H Echinocyamus pusillus H Echinostrephus aciculatus H Dendraster excentricus Primarily deposit feeder, but also preys on...

Hair worms

Phylum Nematomorpha Number of families 2 Parasitic worms as juveniles in marine or terrestrial arthropods, free-living as adults Photo Paragordius varius worms emerging from Gryllus firmus cricket. The worms are undergoing the transition from a parasitic life cycle within the host, to a free-living one. (Photo by Ben Hanelt. Reproduced by permission.) Phylum Nematomorpha Number of families 2 Parasitic worms as juveniles in marine or terrestrial arthropods, free-living as adults Photo...

Moonjelly

Aurelia aurita Linnaeus, 1758, Baltic Sea. The diameter of the medusa swimming bell may reach 20 in (50 cm). The eight lobes of the bell are marked by shallow indentations, each with a rhopalium. The bell is translucent, usually with a pink tinge. The gonads resemble a pink four-leaf clover, as seen inside the semitransparent bell. Hundreds of short, fine tentacles hang in a single circle from the bell margin. The oral arms extend only to about the edge of the bell and may have bright reddish...

Rate of extinctions

The condition of rarity generally precedes extinction of a species, even though passenger pigeons numbered in the millions less than a century before they died out entirely. Endangered species tend to have the smallest populations and are hence the most likely to die out in the short term. While extinctions can occur for a host of reasons, they can be broadly categorized into two types systematic pressures and random events. The former include such human activities as habitat destruction,...

Upsidedownjellyfish

Bigelow, 1892, Jamaica, West Indies. Medusae in the genus Cassiopea are unique in resting bell side down on the ocean bottom. The swimming bell may reach 6 in (15 cm) in diameter. It is flattened, with 40 lappets. The oral arms are about 1.5 times the bell radius. They branch laterally and have numerous tiny tentacle-like projections. The upside-down medusae appear to be clumps of algae because of the bushy greenish brown oral arms that cover the bell. The topside of...

What is a life history

Each animal species can be viewed as a collection of individuals, all sharing a common pool of genes. The genes determine all of the animal's characteristics, and are made of the complex molecule known as DNA. The genes are exchanged among the members of the species through a variety of mechanisms, all of which are related in some way to the process of reproduction. For this reason, the ability to reproduce is often considered to be one of the most important defining characteristics of life....

Elkhorn coral

Madrepora palmata Lamarck, 1816, American Ocean. OTHER COMMON NAMES Spanish Cuerno de alce. Colonial tree-like colonies up to 13 ft (4 m) across and 6.5 ft (2 m) tall, with thick branches broadly flattened near tips to resemble moose or elk antlers tubular coral cups protrude from branch surface. Tissue tan or pale-brown, with tips of branches white. Caribbean Florida Keys, Bahamas, West Indies to Brazil. HABITAT Subtidal zones to 65 ft (20 m) densely aggregated thickets common on windward reef...

Classification of symbioses

Many scientists have attempted to standardize the many conflicting terms that have been used to describe different symbioses, including Ectosymbiosis The partners remain external to each other, such as in lichens. Endosymbiosis The smaller symbionts are inside the host, but remain extracellular. Most of the time en-dosymbionts are in the digestive tract, or inside particular organs. Endocytobiosis is intracellular symbiosis. Symbio-some membranes are the host cell's vacuoles that enclose the...

Cushion star

Patiriella parvivipara Dartnall, 1972. One of the world's smallest known sea stars, measuring up to 0.4 in (1 cm) in diameter with stout arms. They are conspicuous yellow-orange color. Morphologically, they are similar to a co-occurring species Patiriella exigua. Among sea stars, this species has the most restricted distribution. Currently found only within the coastal waters of southern Australia. In either sheltered or exposed shores, usually under small boulders. At low tide, they remain...

Crownofthorns

Size over 16 in (40 cm) in diameter with between 10 and 30 arms covered in dense thorn-like spines, which are mildly venomous can inflict painful wounds that are slow to heal. Red and green coloration with reddish tips to spines. Juveniles are cryptic in color. Tube feet can function in gas exchange and feeding. Pacific and Indian coral reefs, particularly associated with reefs in Hawaii, Australia, the Red Sea, India, and South Africa. Adults found on open sand and feed among coral, whilst...

Organizations

worms0501.htm> American Society of Parasitologists < http asp.unl.edu> American Zoo and Aquarium Association 8403 Colesville Road, Suite 710 Silver Spring, MD 20910 USA < http www.aza.org> Australian Regional Association of Zoological Parks and Aquaria PO Box 20 Mosman, NSW 2088 Australia Phone 61 (2) 9978-4797 Fax 61 (2) 9978-4761 < http www.arazpa.org> British and Irish Graptolite Group c o Dr. A. W. A. Rushton The Natural History Museum, Cromwell Rd. London SW7 5BD United...

Common brittle star

Ophiothrix fragilis Abildgaard, 1789, Denmark. OTHER COMMON NAMES Dutch Gewone brokkelster German Zerbrechlicher Schlangenstern Norwegian Hastjerne. A large brittle star with a disk up to 0.78 in (20 mm) in diameter. The arms are long, colorfully banded and very bristly with seven glassy spines on each segment. Its color varies it may be patterned in red, yellow, orange, violet, gray or brown. Widely distributed in the eastern Atlantic from northern Norway to the Cape of Good Hope also common...

Species accounts

Human Body Cysts The Mouth

Actinia xanthogrammica Brandt, 1835, Sitka, Alaska, United States. OTHER COMMON NAMES Portuguese An mona-verde-gigante. Large, flat oral disk up to 9.8 in (25 cm) diameter column densely covered with hollow adhesive wartlike protuberances known as verrucae tentacles and disk are emerald green, column is olive or brownish. Western coast of North America from Alaska south to Baja California. Low intertidal to shallow subtidal zones on exposed coastlines where it is subject to strong wave action...

Risk assessment

On a practical level, it is difficult to assess which species are most at risk. Because biodiversity encompasses the range of variation, from individuals to populations to habitats themselves, it is virtually impossible to enumerate and quantify. Nevertheless, it is precisely that complexity that is worth conserving. In the absence of long-term data and exact numbers for such ecological parameters as abundance and diversity, conservation efforts usually focus on surrogate species and assume...

Bahama lancelet

Epigonichthys lucayanus Andrews, 1893, Alice Town, North Bimini, Bahamas. (Listed names were originally coined for the European species Branchiostoma lanceolatum. Because of the morphological uniformity of cephalochordates they are usually used for all species.) English Amphioxus, lancelet French Amphioxus, lancelet German Amphioxus, Lanzettfischchen Spanish Anfioxo, pez lanceta, lanceta. Gonads on right side of body only. Sixty (55-62) myotomes 37 (35-52) preatriopore, 16 (13-18) atriopore to...

Sea gooseberry

Agassiz, 1860. Globular in shape with two tentacles (each of which have secondary tentacles). The tentacle sheaths are found at a distance from the infundibulum rather than next to it. Of particular note is that species in this family do not appear to have bioluminescent capabilities (unlike other ctenophores). Surface waters both near shore and open ocean. BEHAVIOR Has the oral end at the opposite end to where the tentacles originate. Due to this, it exhibits a...

Goldenjellyfish

The firm bell is hemispherical and up to 3.5 in (9 cm) in diameter. The bell is translucent with white spots and a granular appearance. The eight oral arms are frilled and flare near the bell, tapering to smooth clublike structures at the end. Tissue along the bell margin and in the frilly oral arms is golden in color, from intracellular algae (zooxanthellae). Tentacles are lacking. This species is found in the tropical southern and central Pacific Ocean and...

Zappas jellyfish

Phialella zappai Boero, 1987, Bodega Bay, California, United States. Hydroid colony simple, unbranched hydranth very extensile, with about 14 tentacles, alternately held upward and downward. Oral part of the hydranth is globular, separated from the rest of the body. Hydrotheca cylindrical, elongated, with an operculum of about seven cusps separated from the hydrothe-cal wall by a thin line, not always evident. Diaphragm present. Pedicel is as long as the hydrotheca or a little shorter,...

Tropical brittle star

Ophiactis savignyi M ller and Troschel, 1842, Egypt, presumably Red Sea. OTHER COMMON NAMES English Savigny's brittle star. A very small brittle star with a disk only 0.039-0.11 in (1-3 mm) in diameter. It usually has six arms, but since it is fissi-parous some individuals that have not completed regeneration may have as few as two arms. Ophiactis has a conspicuous color pattern of green with darker markings and large bare radial shields. Found in all tropical seas. Studies of its genetic...

Black coral

Antipathes fiordensis Grange, 1990, Doubtful Sound, New Zealand. Densely branched tree-like colonies grow to over 16 ft (5 m) tall. Tiny polyps, arranged in rows, are white with six tentacles surrounding a mouth that is raised on an oral cone. Proteina-ceous black skeleton is covered with spines. Endemic to southwestern New Zealand. HABITAT Attached to the walls of fjords from 13 to over 325 ft (4 to over 100 m) in depth (but most abundant between 32-114 ft 10-35 m ). This habitat range is...

Cauliflower coral

Millepora damicornis Linnaeus, 1758, Oceanus Asiatico. OTHER COMMON NAMES English Bird's nest coral, lace coral German Buschkoralle. PHYSICAL CHARACTERISTICS Colonial the colony is a compact clump, up to several meters across, formed of branches the surface is dotted with verrucae (wartlike bumps) that intergrade with the branches. Growth form varies with environmental conditions and geographic location. Tissue color is pale brown, greenish, or pink. Throughout the Indo-Pacific, western and...

Salmonpoisoning fluke

Nanophyetus salmincola Chapin, 1927, dogs, Canis lestes, Procyon psora pacifica, Lynx fasciatu. The ovate adult form of N. salmincola is about 0.03-0.08 in (0.8-2.5 mm) long and about 0.011-0.3 in (0.3-0.8 mm) wide. Two similar-sized suckers are present, one located at the anterior edge, and the other about a third of the way back on the body. The tegument is spiny. The pair of testes are large oval structures that extend from the central to the posterior body. In contrast, a small round ovary...

Species interactions

Competition occurs when organisms require the same limited resources, such as food, living space, or mates or when two groups of organisms try to occupy an ecological niche in the same location at the same time. Competition may either be interspecific (between different species) or intraspecific (within the same species). Hydroids, which have a stolonifer-ous growth pattern, demonstrate two different growth strategies. The first, a guerrilla strategy, is characterized by extensive hydrorhizal...

Feeding mechanisms and behavior

Sea Turbellarian

Lower metazoans demonstrate a remarkable variety of feeding mechanisms. Most sponges are suspension feeders that subsist on such fine particles as bacterioplankton and dissolved organic matter. Sponges acquire food and oxygen from water that flows through them this flow is actively generated by sponges beating their flagella (microscopic whiplike structures). This process also acts as a means of waste removal for sponges. The movement of water through sponges is aided by ambient currents...

Land planarian

Bipalium pennsylvanicum Ogren, 1987, Pennsylvania, United States. Long, brownish yellow in color with three dorsal stripes head is half-rounded or lunate, body retracted and coiled on self at rest, during locomotion over a flat dry surface, the body is greatly extended, undulates, and head is raised above surface moving from side to side head bordered by numerous, small eyes that extend posteriorly along the body mouth with eversi-ble pharynx located in mid-region of body gonopore is just...

Library advisors

Head, Science & Technology Department Carnegie Library of Pittsburgh Pittsburgh, Pennsylvania Linda L. Coates Associate Director of Libraries Zoological Society of San Diego Library San Diego, California Life Sciences bibliographer and head, Seeley G. Mudd Library for Science and Engineering Evanston, Illinois Oklahoma City Zoo Oklahoma City, Oklahoma Charles Jones Library Media Specialist Plymouth Salem High School Plymouth, Michigan Reviewer General Reference teacher Tampa, Florida Richard...

Postembryonic development

Larva Stage Flatworm

Most animal embryos look rather similar to one another up through the stage of gastrulation. It is during the important stages of postembryonic development, however, that the characteristic features of specific phyla, classes, and orders finally emerge. For this reason, much of postembryonic development is said to involve morphogenesis, or the establishment of the animal's definitive body form. Along with the completion of form comes the establishment of function, so that the end result is a...

Sea pansy

Pennatula reniformis Pallas, 1766, Mare Americum. OTHER COMMON NAMES English Atlantic coral. Colonial a large primary polyp up to 3 in (7.5 cm) long and wide has a heart-shaped frond arising from a fleshy stalk. Smaller polyps are embedded in the upper surface of the frond typical octocoral feeding polyps and tiny nonfeeding polyps lacking tentacles. Primary polyp appears purple because of colored sclerites in its tissue. The smaller embedded polyps are transparent. Western Atlantic from North...

Flaskshaped sea cucumber

Rhopalodina lageniformis Gray, 1853, Congo. Unusual flask-shaped holothuroid to 4 in (10 cm) long. Body covered in plates. Mouth and anus adjacent atop a slender stalk above a globose body. Fifteen to 25 digitate tentacles in two concentric whorls. The doubled-over body gives the appearance of 10 radii along the body, unlike the canonical five of other echinoderms. The radii do not cross the ventral pole of the body. Ossicles are small knobby towers. Cruciform plates are present at the ventral...

Venuss girdle

Cestum veneris Lesueur, 1813 ( Cestus veneris Chun, 1879 and 1880). I Cestum veneris I Vallicula multiformis Ribbon-shaped, reaching lengths of 4.9 ft (1.5 m) but only 3.1 in (8 cm) in width. The ctene rows are all on one side of this ribbon, with the mouth on the other. Atlantic, Pacific, Antarctic, and Mediterranean waters. Has an escape behavior that consists of a snakelike undulation of the long body enabling the ctenophore to move several body lengths in seconds. Swims horizontally in the...

Conservation biology

Conservation biology is an interdisciplinary science that attempts to integrate the fields of biology, ecology, economics, and conservation. Scientists Michael Soule and Bruce Wilcox held the First International Conference on Conservation Biology in the United States in 1978 to address such problems as extinction and habitat loss. Those who attended were ecologists and population biologists already studying these issues. The discipline of conservation biology was founded on the principle that...

Giant larvacean

Bathochordaeus charon (Chun, 1900), Cape of Good Hope. Largest of all appendicularians, reaching a length of 1 in (25 mm). Short, broad tail with clearly visible notochord embedded. The gut and gonads are easily seen in the large conspicuous trunk. The house is a series of elaborate tubes and filters used for feeding. A roughly ovoid sheet of mucus that can reach 6.6 ft (2 m) in diameter is continuously secreted above the house for protection and for catching sinking food particles....

Beef tapeworm

Taenia cucurbitina grandis saginata Goeze, 1782, Germany. Tae-niarhynchus saginatus (Goeze, 1782) Weinland, 1858. French T nia inerme German Rinderbandwurm. PHYSICAL CHARACTERISTICS Body usually 9.8-16 ft (3-5 m) long (exceptionally, some specimens reach a length of 66 ft 20 m ), with maximum width (0.20-0.28 in 5-7 mm ) at gravid proglottides. Scolex lacks rostellum and hooks. Gravid proglottides (found in feces of humans) can be distinguished from those of the other common human Taenia, T....

Rubber coral

Palythoa caesia Dana, 1846, Feejee Islands. OTHER COMMON NAMES English Palythoa sea mat Mat-like colonies appear rubbery in texture typically form ovoid blobs 2-4 in (5 10 cm) in diameter. Polyps are completely embedded in thick coenenchyme encrusted with sediment short, simple tentacles with knobbed tips. Color ranges from dark brown to tan. Intertidal or subtidal zones on coral reefs and reef crests. In areas of high abundance, may form mats covering virtually all of the available substrate...

Acknowledgements

Gale would like to thank several individuals for their important contributions to the volume. Dr. Dennis A. Thoney, topic editor for the Lower Metazoans and Lesser Deuteros-tomes volume, oversaw all phases of the volume, including creation of the topic list, chapter review, and compilation of the appendices. Neil Schlager, project manager for the Lower Metazoans and Lesser Deuterostomes volume, and Vanessa Torrado-Caputo, associate editor at Schlager Group, coordinated the writing and editing...

Color graphics enhance understanding

Grzimek's features approximately 3,000 color photos, including nearly 110 in the Lower Metazoans and Lesser Deuterostomes volume 3,500 total color maps, including approximately 130 in the Lower Metazoans and Lesser Deuterostomes volume and approximately 5,500 total color illustrations, including approximately 350 in the Lower Meta-zoans and Lesser Deuterostomes volume. Each featured species of animal is accompanied by both a distribution map and an illustration. All maps in Grzimek,s were...

Heart urchin

Coloration usually brownish yellow. Oval shaped with dense coat of fine spines that keep sediment clear of test during burrowing activity. Limited distribution. Endemic to the Kerguelen Islands, Antarctica. Inhabits shallow inlets and bays, living buried in fine sand usually protected from wave swell. Little known, but lives within dense populations. Little known but other species belonging to the genus Abatus are deposit feeders, usually gathering detritus...

Giant medusan worm

Reproduction Biology

Holothuria maculata (Chamisso and Eysenhardt, 1821), Marshall Islands, Micronesia. Three subspecies recognized. OTHER COMMON NAMES German Wurmseegurke. An unmistakable species, the longest sea cucumber with a maximum length of 10 ft (3 m), although most animals reach only approximately 3-5 ft (1.0-1.5 m) long. This sea cucumber is serpentine and a mottled light and dark brown. There are 2040 tentacles, which are feather-like. Ossicles are anchors and oblong perforated plates as well as tiny...

Longspined sea urchin

H Abatus coratus H Astropyga magnifica H Anthocidaris crassispina English Blue eye urchin, black long-spined urchin. PHYSICAL CHARACTERISTICS Relatively flattened, but oval test that can reach 3.1 in (8 cm) in diameter. Distinctive long and slender black or while spines, which vary in length from 1.9-3.9 in (5-10 cm). Test and spines are fragile. It has a distinctive iridescent blue ring around anus. Often mistaken for D. steosum, which has an orange ring. Darker animals tend to exist in the...

Thimble jelly

Thimble Jellyfish Larvae

Linuche unguiculata Schwartz, 1788, American Tropical Atlantic. The medusae grow only to 1 in (2.5 cm) in height. As the name implies, they are thimble-shaped, with a shallow groove near the top of the bell. They have eight very short tentacles and eight rhopalia alternating between the 16 lappets at the bell margin. The outside of the bell is transparent, with numerous warts of stinging cells. The inner part of the bell is white with greenish brown spots. The polyps form colonies and are...

Info

H J J ' 1 i- * rfliZS , TT- li H J J ' 1 i- * rfliZS , TT- li 1. Crown-of-thorns (Acanthaster planci) 2. Cushion star (Oreaster reticulatus) 3. Sand star (Astropecten irregularis)-, 4. Sunflower star (Pycnopodia helianthoides) 5. Northern Pacific sea star (Asterias amurensis). (Illustration by Barbara Duperron) 1. Blue starfish (Linckia laevigata)-, 2. Cushion star (Odontaster validus) 3. Cushion star (Patiriella parvivipara) 4. Velcro sea star (Novodinia an-tillensis) 5. Ocher star (Pisaster...

Sea urchins and sand dollars

Phylum Echinodermata Class Echinoidea Number of families 46 Ubiquitous, spine-covered animals that often live beneath the sand surface or hide out in rocky crevices and sea grass beds Photo Red sea urchin (Strongylocentrotus francis-canus) ( Shedd Aquarium Photo by Patrice Ceisel. Reproduced by permission.) Phylum Echinodermata Class Echinoidea Number of families 46 Ubiquitous, spine-covered animals that often live beneath the sand surface or hide out in rocky crevices and sea grass beds Photo...

Gametogenesis

During sexual reproduction, each parent animal must form specialized cells known as gametes, which are genetically re-combined and in which the chromosome number is reduced by half from a diploid double set to a haploid single set. Both processes occur during meiosis, which is the first stage of ga mete formation, or gametogenesis. In virtually all animals that reproduce sexually, the gametes occur in two morphologically distinct forms corresponding to male and female. These distinctions in...

Appendices and index

In addition to the main text and the aforementioned Glossary, the volume contains numerous other elements. For further reading directs readers to additional sources of information about lower metazoans and lesser deuteros-tomes. Valuable contact information for Organizations is also included in an appendix. An exhaustive Lower Meta-zoans and Lesser Deuterostomes order list records all orders of lower metazoans and lesser deuterostomes as recognized by the editors and contributors of the volume....

Six keyhole sand dollar

Thin and flattened disc with six characteristic slot-like holes and distinctive pentaradiate or petal-like pattern tube feet on upper surface. Diameter is up to 3.9 in (10 cm). Yellow to light brown in color. Occurs along coastal waters of the western Atlantic from North Carolina to Uruguay. Subtidally to a depth of 200 ft (60 m). Commonly found inhabiting open sandy areas clear of algae. Burrows vertically into sand to several inches (centimeters) below surface. Species is host to the crab,...

Conservation status

No species are listed by the IUCN Red List. For most Hy-drozoa, the distribution and the abundance are not known and only the few remaining specialists know about their presence. Many species are endemic simply because they are not searched for and only the areas of activity of specialists are covered. The only groups mentioned in regional or national red lists are the calcified, coral-like Milleporidae and Stylas-teridae, which are also listed by CITES. Inclusion of these taxa on conservation...

References Books

Atlas of Invertebrate Reproduction and Development. 2nd ed. New York Wiley-Liss, 2000. Gilbert, Scott F., and Anne M. Raunio, eds. Embryology Constructing the Organism. Sunderland, MA Sinauer Associates, 1997. Strathmann, Megumi F., ed. Reproduction and Development of Marine Invertebrates of the Northern Pacific Coast. Seattle University of Washington Press, 1987. Wilson, W. H., Stephen A. Sticker, and George L. Shinn, eds. Reproduction and Development of Marine...

Significance to humans

Hidradenitis Illustration

It is documented that the heteronemertean, Cerebratulus lacteus, (tapeworm) was frequently collected and used as bait by sport fishermen in the United States, at least into the middle of the twentieth century. Another large heteronemertean used as bait in South Africa and Mozambique is Polybra-chiorhynchus dayi, also referred to as tapeworm by fishermen. Other uses of anoplan nemerteans are not known. 1. Tubulanus annulatus 2. Lineus longissimus 3. Baseodiscus delineatus. (Illustration by John...

Cephalochordata

Phylum Chordata Class Cephalochordata Number of families 1 Exclusively marine species with slender, fish-like shape, tapered at both ends easily recognized by the externally visible v-shaped lines that separate the iterated muscle blocks and by the oral cirri that guard the mouth opening against unwarranted particles Photo Lancelet (Amphioxus lanceolatus) larva head. Lancelets have no heart but do have gills. (Photo by Animals Animals P. Parks, OSF. Reproduced by permission.)

Sea apple

Colochirus violaceus (Theel, 1886), Philippines. Synonyms include P. axiologus, P. arae, P. bicolor, and P. tricolor. French Pomme de mer German Seeapfel. A large, colorful species to 7 in (18 cm) long. Color is variable, often purple. There are three ventral, longitudinal rows of tube feet. The dorsal side has two rows of papillae and small scat tered papillae. The body is curved in life so that the mouth and anus point upward. The 10 tentacles are bushy purple to red with white tips....

And humans

Marine organisms from all marine phyla have been a source of food since humans first began to explore marine environments. In stark contrast to terrestrial plants and animals that have been widely used for remedies of human disorders the World Health Organization (WHO) estimates that 60-80 of the world's population relies primarily on plants for their basic health care only a small number of marine species have been used for medicines, mostly due to human's limited access to marine resources....

B

A hoplonemertean attacking the crab Uca musica. A. The everted proboscis rapidly entwines the prey and the stylet injects toxins to immobilize the prey, and probably injects digestive enzymes at the same time. B. The struggle is over and the worm inverts its proboscis. C. The worm emerges and searches for a place to enter the crab, whose tissues will be drained in about an hour. (Illustration by Emily Damstra) mainly on crustaceans. The proboscis is everted and the central armature (the stylet)...

Stalkedjellyfish

Haliclystus auricula Rathke, 1806, Norway. In the Stauromedusae the medusa is stalked and remains attached to the substrate. The bell (calyx) is funnel-shaped and grows to 1.25 in (3 cm) in diameter, with the mouth at the bottom of the funnel. The calyx has eight arms, with clusters of 30-80 knobbed tentacles at the tips. Between the arms are eight bean-shaped sticky pads. The stalk is as long as the calyx is wide. The color of this jellyfish often matches the substrate green, brown, yellow, or...

Standards employed

In preparing the volume on Lower Metazoans and Lesser Deuterostomes, the editors relied primarily on the taxonomic structure outlined in Invertebrates, edited by R. C. Brusca, and G. J. Brusca (1990). Systematics is a dynamic discipline in that new species are being discovered continuously, and new techniques (e.g., DNA sequencing) frequently result in changes in the hypothesized evolutionary relationships among various organisms. Consequently, controversy often exists regarding classification...

Reproductive duality

Many animals, particularly the lower metazoans, actually use both asexual and sexual reproduction at various times. This reproductive duality gives them the advantages of both modes. It is rare for both asexual and sexual reproduction to occur simultaneously, however. In many lower metazoans, the asexual and sexual processes are cyclical, occurring in different seasons. Examples include many marine sponges (phylum Porifera), in which a single individual may alternate between reproductive modes....

Asexual reproduction

Fundamentally, reproduction is the copying of an individual animal's DNA combined with transferring the copy into a newly formed individual. In some cases, the copy of the DNA is nearly exact, and the offspring develop from a single parent. This is typically the case in what is known as asexual reproduction. In its truest form, asexual reproduction involves simple cell division, or mitosis, without any reorganization of DNA fragments during the process. Asexual reproduction also involves only...

Liver fluke

Fasciola hepatica Linnaeus, 1758, in aquis dulcibus ad radices lapidum, inque hepate pecorum. Diss. de Ovibus Europe. English Sheep liver fluke French Grande douve du foie, douve du foie de mouton German Gro er Leberegel. Adult liver flukes may reach 1.7-2.2 in (4-5 cm) in length and 0.6 in (1.5 cm) wide. They are typically about 1.3 in (3 cm) long, 0.4 in (1 cm) wide, and have a spiny tegument. They taper toward the rear. The front end bears an oral sucker and a cone-shaped tip. The sucker on...

Doliolid

Dolioletta gegenbauri (Uljanin, 1884). Barrel-shaped, clear, gelatinous body about 0.35 in (9 mm) in length with eight prominent muscle bands in the asexual stage and the 0.47-in (12-mm) sexual stage has nine muscle bands. Semi-cosmopolitan in cool waters of both hemispheres. (Specific distribution map not available.) Little is known about vertical distribution, but commonly found in oceanic surface waters. Known for their jumpy swimming pattern when disturbed. Swims by contracting muscle bands...

Types of symbioses

The term symbiosis was, in a broad sense, originally intended by Anton de Bary in 1879 to refer to different organisms living together. Proposals to change this definition and redefine symbiosis, such as equating it to mutualism, have led to confusion. Various types of symbioses, whether beneficial or harmful, are described by the terms commensalism, mutualism, and parasitism. The term commensalism was first used by P. J. van Beneden in 1876 for associations in which one animal shared food...

Oriental liver fluke

Some scientists now use the genus designation Opisthorchis for this fluke. English Chinese liver fluke French Douve du foie chinoise, douve du foie orientale German Chinesischer Leberegel. The adults are flattened cigar-shaped flatworms 0.4-1.0 in (10-25 mm) long and 0.1-0.2 in (3-5 mm) wide. The pointed front end has an oral sucker at its tip. Much of the anterior half of the animal is filled with a looping uterus. A small, slightly lobed ovary follows with...

Dog tapeworm

Hydatigena granulosa Batsch, 1786, Germany. OTHER COMMON NAMES French T nia chinocoque German H lsenwurm. PHYSICAL CHARACTERISTICS Adult 0.12-0.24 in (3-6 mm) long, consisting of scolex, short neck, and three to five proglottides. Scolex bearing 30-36 (rarely more) rostellar hooks. Gravid proglottis highly elongate. Microhabitats are intestines of carnivore mammals, mostly of the family Canidae (dogs, wolves, jackals, etc). Larvae occur in internal organs (liver, lungs, musculature) of...

Sexual maturation

After the embryo or larva is transformed into a juvenile form, all that remains for the individual is maturation of its sexual reproductive systems, accompanied or followed by mei-otic maturation of the gametes to form fully functional and fertilizable sperm and oocytes. The mechanisms for maturation vary widely among animal phyla, but are especially diverse among the lower metazoans. Such phyla as placozoans and sponges have no discernible gonads the gametes simply form out of previously...

Cod worm

Ascaris's decipens (Krabbe, 1878), originally Cristophora cristata, Greenland coast. Latest name Pseudoterranova decipens. OTHER COMMON NAMES English Seal worm. Often found in cod, but are also found in many other species of fish. In the larval stage, they are 0.20-2.28 in (5-58 mm) in length by 0.012-0.047 in (0.3-1.2 mm) in width, and yellowish, reddish, or brownish in color. They have well-developed and distinct lips. The excretory system is elongated and cord-like, while the adult esophagus...

Cestoda

Photo Light micrograph of the scolex of an adult pork tapeworm (Taenia solium). At the top are the hooks, at lower left and right are the rounded suckers. These are used by the tapeworm to attach itself to the intestinal walls of its host. Humans are the main host of this parasite, which infects some four million people worldwide. (Photo by Alfred Pasieka Science Photo Library Photo Researchers, Inc. Reproduced by permission.)

Lancet fluke

Dicrocoelium dendriticum Rudolphi, 1819, intestine of Xiphias gladius, a swordfish (probably in error). English Lancet liver fluke French Petite douve du foie German Kleiner Leberegel, Lanzettegel. Adult lancet flukes have translucent bodies shaped like long, thin leaves. Both oral and ventral suckers are located toward the front of the body, with the foremost oral sucker a bit smaller than the others. This species averages about 0.02-0.06 in (5-15 mm) long and 0.04-0.08 in (1-2.5 mm) wide....

Summary

The lower metazoans comprise animals that are thought to lie relatively close to the evolutionary root of animals as a whole. While they all have their own specializations, it is possible, and to be hoped for, that they retain some features that were characteristic of the very earliest stages of metazoan and bilaterian evolution. Although it is widely accepted that the sponges are basal within the animals, broadly followed by the ctenophores and cnidarians, the relationships of the bilateri-ans...

Contents

viii Contributing Volume 1 Lower Metazoans and Lesser Deuterostomes What are lower metazoans and lesser deuterostomes 3 Evolution and Reproduction, development, and life Lower metazoans, lesser deuterostomes, and humans 44 Conservation Class Class Class Class Class Class Class Phylum Class Class Class Class Class Class Class Phylum Phylum Phylum Class Class Phylum Phylum Phylum Phylum Phylum Phylum Phylum Phylum Class Class Class Class Class Class Phylum Phylum Phylum CHORDATA Subphylum...

Sexual reproduction

In most cases, the DNA copy is not exact, so that the genetic makeup of the newly formed offspring differs from that of its parent. This programmed variability is accomplished primarily by sexual reproduction. The genetic process that defines sexual reproduction occurs only during a very brief specialized phase of cell division, and only within cells belonging to the germ cell line. A germ cell is defined as a cell belonging to a cellular lineage that, at some point, will deviate from normal...

Foreword

No one knows exactly how many distinct organisms inhabit our planet, but more than 5 million different species of animals and plants could exist, ranging from microscopic algae and bacteria to gigantic elephants, redwood trees and blue whales. Yet, throughout this wonderful tapestry of living creatures, there runs a single thread Deoxyribonucleic acid or DNA. The existence of DNA, an elegant, twisted organic molecule that is the building block of all life, is perhaps...

Deep water reef coral

Madrepora pertusa Linnaeus, 1758, type of locality not stated, but probably the fjords of Norway. English Spider hazards, spiders' nests (Nova Scotia) Norwegian Glasskorall, 0yekorall. Colonial irregularly branched to form bushy or tree-like colonies up to 2 m tall brittle tubular branches about 0.5 in (1-1.5 cm) thick white or pink. Most records are from the North Atlantic, but also known from the South Atlantic, northwestern Pacific Indian Ocean and waters south of New Zealand. Cold water...

Subject advisors

Volume 1 Lower Metazoans and Lesser Deuterostomes Dennis A. Thoney, PhD Director, Marine Laboratory & Facilities Humboldt State University Arcata, California Assistant Professor, Department of Biological Sciences Humboldt State University Arcata, California Dennis A. Thoney, PhD Director, Marine Laboratory & Facilities Humboldt State University Arcata, California Research Associate, Department of Entomology Smithsonian Institution Washington, DC Research Associate, Department of...

Roundworms

Phylum Nematoda Class Adenophorea Number of families 96 Primarily free-living marine, freshwater, and terrestrial nematodes considered to be the most primitive form of nematodes Photo Trichina worm (Trichinella spiralis) in muscle tissue section. (Photo by Bob Gossington. Bruce Coleman, Inc. Reproduced by permission.)

Dog hookworm

Sclerostoma caninum (Ercolani, 1859), originally Sclerostoma Ca-nis familiaris, Europe. English Creeping eruption (when found in humans). The most widespread of the hookworm species, they target dogs and other canids. Male adults are 0.43-0.55 in (1.1-1.4 cm) in length, with a copulatory bursa, two large lateral lobes, and two equal filiform spicules females 0.5-0.8 in (1.3-1.9 cm) in length, with no vulvular flap. Adults have an anterior end that is bent dorsally, a buccal capsule that is deep...

For further reading

Invertebrate Learning A Laboratory Manual and Source Book. Washington, DC American Psychological Association, 1990. -. A Primer of Invertebrate Learning The Behavioral Perspective. Washington, DC American Psychological Association, 1994. Abramson, C. I., and I. S. Aquino. A Scanning Electron Microscopy Atlas of the Africanized Honey Bee (Apis mellifera) Photographs for the General Public. Campina Grande, PB, Brazil Arte Express, 2002. Abramson, C. I., Z. P. Shuranova, and Y. M....

African river blindness nematode

Filiria volvulus (Lenckart in Mason, 1893), originally Filaria Homo sapiens, West Africa. OTHER COMMON NAMES English River blindness nematode. Filarial parasites of primates, primarily humans. They have an adult length of 0.8-27.6 in (2-70 cm) with females measuring 13.0-27.6 in (33-70 cm) in length by 0.011-0.016 in (270-400 pm) in width males measure 0.8-1.6 in (2-4 cm) in length by 0.00512-0.00827 in (130-210 pm) in width. Microfilariae measure 0.00866-0.0142 in (220-360 pm) in length by...

Cannonballjellyfish

Agassiz, 1862, Atlantic Ocean, East Coast of United States. OTHER COMMON NAMES English Cabbagehead jellyfish. The firm, almost spherical swimming bell grows up to 7 in (18 cm) in diameter and lacks tentacles. The oral arms are fused to form a rigid, short mound below the bell. The bell color ranges from nearly white to bluish, and it may darken to reddish orange with blue speckles toward the bell margin the oral arms are white. The cannonball jellyfish occurs in...

Brittle and basket stars

Phylum Echinodermata Class Ophiuroidea Number of families 16 Small- to medium-size echinoderms with a flattened disk often covered with a series of scales, granules and small spines usually five long thin (in comparison with the disk) articulated arms that break off easily a row of papillae (small nipple-shaped structures) known as the arm comb near the base of each arm lower surface of the disk containing a central mouth leading to the stomach pouch mouth divided by five jaws Photo The snake...

Some examples of symbiosis in lower metazoans and tunicates

Sharing of food and the provision of shelter are two main features of commensalistic relationships. Many species that display commensalistic relationships inhabit the internal spaces of sponges, clams, and sea cucumbers. The symbionts are often smaller and more streamlined than their free-living relatives and show evidence of long-term associations. For example, there are crab and shrimp species that live in the mantle cavities of bivalve mollusks the pearl fish, Corpus, shows both structural...

Red soft tree coral

Spongodes hemprichi Klunzinger, 1877, Red Sea. OTHER COMMON NAMES German Hemprichs Schleierbaumchen Italian Alcionario rosa. Highly-branched, fleshy, arborescent (treelike) colony lacking an axial skeleton large embedded sclerites are visible in branches and are conspicuous in polyps, producing a spiky appearance polyps are not retractile and are mainly clustered in bundles at the end of branches translucent, colors vary from red to pink, orange, or violet. Found only in strong currents, often...

Spaghetti worm

Saxipendium coronatum Woodwick & Sensenbaugh, 1985, near Rose Garden geothermal vent, Gal pagos Rift, at a depth of 8130 ft (2478 m). OTHER COMMON NAMES Italian Verme tentacolato. A long thin yellowish-white hemichordate, this species can reach 6.6-9.8 ft (2-3 m) in length. The proboscis is tapered to a soft point toward its front, and the collar is short. Found near hydrothermal vents in the deep sea, loosely attached to rocks. Little is known about the behavior of this species, but...

Western sand dollar

Dendraster excentricus Eschscholtz, 1831. OTHER COMMON NAMES English Eccentric sand dollar. Rigid test measuring up to 3.5 in (9 cm) and covered with moveable spines. Pale gray-lavender to dark purplish black coloration characteristic pentaradiate or petal-shaped pattern tube feet on upper surface of test. Northeastern coasts of the Pacific ocean from southern Alaska to Mexico. Found in depths between 130-295 ft (40-90 m). Inhabits sandy bottoms within sheltered bays, lagoons, and open coastal...

Barbers pole worm

Strongylus contours (Rudolphi, 1803), originally Strongylus ovis-aries ( ), Europe. English Barber pole worm, sheep stomach worm, wire worm. PHYSICAL CHARACTERISTICS A stomach parasitic roundworm found inside ruminants such as sheep, goats, cattle, and wild ruminants. Males have a length of 0.7-0.8 in (18-21 mm) females 0.7-1.2 in (18-30 mm). Females possess white uteri and ovaries that spiral around their red blood-filled intestine, which gives a twisted (barber pole) appearance. The small...

Blue starfish

Usually five arms with a body diameter that can reach 12 in (30 cm). Adults have brilliant blue coloration. Juveniles are blue-green, purplish with dark spots. The genus Linckia has many color morphs, making it difficult to identify species. Common in shallow waters of Indo-Pacific Oceans. In particular, eastern Africa to Hawaii and the South Pacific Islands to Japan. Adults found along coral gravel substrates of reef terraces in direct sunlight, sandy...