Physical characteristics

Most sea cucumbers are soft bodied and worm- or sluglike. Some tropical species have thick, muscular body walls, whereas many deep-sea forms are gelatinous and transparent. Most species are perhaps 20 in (15 cm) long, although some apodans are as small as a few millimeters or, in one species, Synapta maculata, more than 118 in (3 m) long. Another species in the aspidochirote Stichopodidae, Thelenota anax, may weigh more than 11 lb (5 kg). Although the description echinoderm worms is apt, some...

Glossary

4d cell Mesentoblast a blastomere cell that results from zygotes that have spiral cleavage divisions, and contains an unidentified cytoplasmic factor that causes the cell and its progeny to form mesoderm. Abdomen The posterior of the main body divisions. Abyssal Of, or relating to, the deepest regions of the ocean. Acanthor First larval stage of acanthocephalans. Aciculum Small needlelike structure resembling a rod that supports the divisions of the parapodium. Acoelomate An organism,...

Phytosynthetic associations

Hydra are common inhabitants of freshwater lakes and ponds, where they feed on small animals. Hydra viridis contains the green alga Chlorella. Algae reproduces asexually within the gastrodermal cells and a single hydra may contain about 150,000 algal cells. Under normal conditions, symbiotic algae are not digested by hydra. There are two reasons for this first, the cell wall of algae contains sporopollenin, a protein that resists digestive enzymes second, vacuoles containing algae do not fuse...

Significance to humans

Reproduction Biology

Although several hundred reports exist of humans supposedly infected with gordiids, humans do not serve as hosts for these worms. Most, if not all, of these cases are due to incidental associations. Worms have been noted from the human digestive tract by being spit up or passed through the intestine. These worms are likely to have been swallowed as adults. No evidence exists that these worms are able to live within a human for an extended period. It is also likely that worms discovered in...

Elephant ear polyps

Amplexidiscus fenestrafer Dunn and Hamner, 1980, Lizard Island, Great Barrier Reef, Australia. English Giant elephant ear mushroom anemone, disk anemone French An mone disque German Grosses Elefantenohr Italian Anemone orecchio d'elefante. Short, column up to 2 in (5 cm) tall. Oral disc typically 8-10 in (20-25 cm), but as much as 18 in (45 cm), in diameter mouth atop a raised cone. 15-20 tentacles around the margin, and many short, conical tentacles arranged in radial rows on the oral disc. A...

Glass sponges

Glass Sponges

Hexactinellids (glass sponges) are deepwater marine sponges that have skeletons of siliceous (glass) spicules with a distinctive triaxonic (cubic three-rayed) symmetry. Unlike the other two main classes of sponges (Calcarea and Demospongiae), glass sponges lack either a calcareous or organic skeleton. Furthermore, glass sponges are highly unusual in that their major tissue component is a giant syncytium (see below) that ramifies throughout the entire body, stretching like a cobweb over the...

Echinostome

Echinostoma revolutum Froelich, 1802. OTHER COMMON NAMES French Fchinostome. Adult echinostomes range from 0.24-1.3 in (6-30 mm) long and 0.02-0.06 in (0.6-1.6 mm) wide. Echinostomes have a tegument (outer surface) carrying spines or papillae (small rounded projections) and an anterior collar consisting of 37 spines arranged in a characteristic pattern. The ventral sucker is slightly behind the oral sucker. The uterus takes up much of the front half of the body and two testes follow, one after...

No common name

Amphilina Foliacea

Monostomum foliaceum Rudolphi, 1819, Italy. Body monozoic, dorso-ventrally flattened, oval or leaf-shaped in outline, 1-2.6 in (28-65 mm) long and 0.67-1.2 in (17-30 mm) wide. Anterior end pointed, with slightly expressed apical invagination. Uterine orifice situated in anterior end. Orifice of ejaculatory duct on posterior end. Vaginal pore postero-lateral, at some distance from male pore. Adults are parasitic in the body cavity of sturgeons (Acipenser sturio, A. nudiventris, A. ruthenus, A....

Resources Books

Loriolella, and the Transition from Regular to Irregular Echinoids. In Echinoderm Research, Proceedings of the 5th European Conference on Echinoderms, edited by Maria D. C. Carnevali and Francesco Bonasoro. Rotterdam A. A. Balkema, 1999. Birkeland, C. The Influence of Echinoderms on Coral-reef Communities. In Echinoderm Studies, edited by Michael Jangoux and John Lawrence. Rotterdam A. A. Balkema, 1989. Ebert, T. A. Recruitment in Echinoderms. In Echinoderm Studies, edited by...

Feeding ecology and diet

Holothuroids are either deposit feeders or suspension feeders. Approximately 33 percent of species are suspension feeders, nearly all of them within Dendrochirotida. This group has richly branched tentacles that are lightly coated in mucus and extend into currents to capture algae, planktonic animals, or organic matter. Food is captured passively on mucus-coated sites on the tentacles or mechanically. The tentacles are brought into the mouth one at a time and are wiped clean by contracting...

Citrus spine nematode

Criconema civellae (Steiner, 1949), Greenhouse, Beltsville, Maryland, United States. Latest name Crossonema civellae, Menta and Raski, 1971. Females are of length 0.0114-0.0339 in (0.29-0.86 mm), with 40-93 annules. Contains spear muscles that are well developed and large compared to other species. The muscles are 0.000591-0.00394 in (15-100 pm) in length. The labial cap is not easily distinguished from the overall body contour, except for a narrowing that leads to the oral disk. The esophagus...

Rattailed sea cucumber

Chiridota oolitica (Pourtales, 1851), Florida, United States. A brownish gray to reddish black, sausage-shaped sea cucumber to 6 in (15 cm) long with 15 digitate tentacles and a small, sometimes indistinct tail. The body surface is smooth. The tail and oral region usually are somewhat lighter in color than the rest of the body. Body color is age related older individuals often are darker as a result of the presence in the body wall of microscopic phosphatic bodies that replace the calcareous...

Reproductive biology

The majority of cestodes are hermaphroditic (only the members of the tetraphyllidean family Dioecotaeniidae and the cyclophyllidean family Dioecocestidae are dioecious). As a rule, each proglottis contains one set of male reproductive organs and one set of female reproductive organs. Often the maturation of the male organs and female organs do not coincide in time. In the majority of the families, the male organs mature first and proglottides initially act as male. This type of strobilar...

Ikaite rotifer

Notholca ikaitophila Sorensen and Kristensen, 2000, Ikka Fjord, Greenland. I Seison nebaliae I Asplanchna priodonta I Notholca ikaitophila Measures 0.00744-0.00925 in (189-235 pm). The species has a well-developed lorica, but the feet and toes are completely reduced. The lorica is rounded posteriorly and has six spines on the dorsal edge of the anterior opening. The dorsal plate is ornamented with a distinct longitudinal striation and a pair of lateral movable spines. Trophi belong to the...

Evolution and systematics

Turbellaria Structure

The phylogeny of the platyhelminth classes is not clear. Recent morphological and molecular studies have generated numerous hypotheses as to their relation to each other and to other phyla. Traditionally, the class Turbellaria was thought to be the basal ancestor of the parasitic classes (Trematoda, Cestoda, Monogenea) within the phylum. However, some researchers believe that the parasitic classes should be separated into a separate phylum (Neodermata) based on their unique tegument, the...

Common Name Of Polystoma Integerrimum

Polystoma integerrimum Froelich, 1791 Rudolphi, 1808. Adult about 0.39 in (10 mm) in length. Haptor has six muscular suckers, one pair of hamuli and 16 hooklets, each sucker containing one hooklet. Oral sucker around mouth. Testis follicular. Likely to be present wherever its specific host, the brown frog, Rana temporaria, occurs, but not systematically mapped. Bladder of Rana temporaria. BEHAVIOR Adult parasite accumulates reserves, but assembles no eggs while frog is living on land during...

Rat lungworm

Pulmonema catonesis (Chen, 1935), Dominican Republic, originally Pulmonema raltucnorvegicus, Canton, China. Moderate sized, adult males measure 0.79-0.87 in (20-22 mm) in length by 0.0126-0.0165 in (320-420 pm) in width, and adult females measure 0.87-1.34 in (22-34 mm) in length by 0.0134-0.0221 in (340-560 pm) in width. Distribution can only be identified by the disease caused by this species, which has been reported in Asia (Philippines, Indonesia, Malaisia, Thailand, Vietnam, Taiwan,...

Salp

Both stages possess a clear, barrel-shaped, gelatinous body with circular muscle bands embedded in the body wall. Solitary (asexual) stage 0.39-1.9 in (1-5 cm) in length with nine muscle bands. Aggregate form (sexual) 0.39-1.5 in (1-4 cm) long with six muscle bands and can be found solitary after breaking off long chain. The body shape of the solitary (asexual) stage is symmetrical it is asymmetrical for the aggregate (sexual) stage, with short outerior and posterior projections. Gut is the...

Blackspot flatworm

Uvulifer ambloplitis (Hughes 1927) Ceryle alcyon, Helisoma trivo-lvis, H. campanulatum, Ambloplitis rupestris, Micropterus dolomieu, Aplites salmoides, Eupomotis gibbosus, Apomotis cyanellus, Enneacan-thus obesus. OTHER COMMON NAMES English Black grub. Adults are spoon-shaped with a broad body, thinner neck, and a slightly broader cocked head. The oral sucker is small and foremost on the fluke, with a small ventral sucker about halfway back on the head, and a holdfast organ just behind the...

Rock boring urchin

Echinostrephus aciculatus Agassiz, 1863. OTHER COMMON NAMES English Needle-spined urchin, reef boring sea-hedgehog. Flattened and circular test up to 3.1 in (8 cm) in diameter. Has black to reddish purple coloration with rigid needle-like spines. Indo-Pacific coastal waters to a depth of 165 ft (50 m). HABITAT Bores into rock to create living-chamber. Uses spines on its upper surface as defense against predators. As they grow, individuals can become trapped in chamber. Dependent on catching...

Sea biscuit

English Heart urchin, long-spined sea biscuit, great red-footed urchin. One of the largest irregular urchins longest dimension is their oval-shaped test that can reach 9.8 in (25 cm) in length. Colors vary from yellow or tan to reddish brown. Test covered with medium-sized spines, although some on the upper surface are up to 3.9 in (10 cm) long. Flat underneath with five rows of tube feet in ambulacral groove. Found in shallow waters from Florida to the West Indies and Brazil. Common at depths...

Spicules

Anatomy Glass Sponges

The larva of a hexactinellid sponge. (Illustration by Emily Damstra) laminar proteinaceous structure. While it undoubtedly serves as a partial barrier to the free exchange of materials, electric currents can flow through it and transport vesicles are able to move through pores in its structure. Between cellular and syn-cytial components of the sponge there is a very thin collagen layer, the mesohyl. This layer is believed to be too thin for cells to migrate within, as is the case with other...

Canine heartworm

Filaria immitis (Leidy, 1856), Canis familiaris, United States. OTHER COMMON NAMES English Dog heartworm. Females are 9-12 in (25-30 cm) in length by only about 0.13 in (5 mm) in width, while males are about half the size of females with a length of 5-6 in (12-16 cm). They have somatic (coelomyarian) muscles. (Somatic muscles provide the shape to individual muscle cells thus, supplying a portion of the hydrostatic skeleton in nematodes). Specifically, coelomyarian mus cles (a type of muscle...

Tuxedo pincushion urchin

OTHER COMMON NAMES English Royal urchin, sphere urchin, globular sea urchin, ball sea-hedgehog. Test can reach 2.3 in (6 cm) in diameter and has five to 10 broad bands of bright blue coloration with bands of reddish-brown spines, which give it a very striking appearance. Coastal waters of China, Japan, Indian Ocean, and the Philippines. During the day will hide among rocks, rubble, and in crevices associated with coral reefs. Solitary animal. Camouflages test...

Pelagic sea cucumber

Pelagothuria natatrix Ludwig, 1894, Gulf of Panama, Eastern Pacific Ocean below 2,000 ft (610 m) depth. A bizarre, transparent sea cucumber 2-3 in (5-8 cm) long with 12-16 webbed papillae exceeding the body's length and forming a veil around the mouth. This sea cucumber is slender and pale pinkish purple. The tentacles are two-pronged and number approximately 15. Ossicles and a calcareous ring are absent. Western Indian Ocean to eastern Pacific Ocean and Atlantic Ocean at subtropical to...

Animal evolution

Aposematic Coloration Animals

Because of their long history and enormous adaptability, animals are organized in a remarkable number of different ways, ranging from simple sponges with only a few cell types through to the vertebrates with their complex nervous and immune systems. Indeed, it is possible to arrange animals in a broad series, from organisms that do not possess true tissues (e.g., sponges), through organisms with tissues but no organs (e.g., cnidarians), into the bilaterally symmetrical animals (the Bilateria)...

Magnificent sea anemone

Actinia magnifica Quoy and Gaimard, 1833, Vanikoro, Santa Cruz Islands, New Hebrides. English Bulb-tip anemone, maroon anemone, Ritteri anemone German Prachtanemone Local dialects Rambu-rambu (Indonesia), Burin (Malaysia) Oral disc up to 39 in (1 m) in diameter column as much as 8 in (20 cm) tall and wide at the base tentacles 3 in (7.5 cm) long, of uniform thickness with blunt or slightly bulbous tips. Brightly colored column may be avocado green, magenta, cerulean blue, or white, with yellow,...

Aggressive and defensive behavior

Gastropods, pycnogonids, sea stars, sea urchins, fishes, and sea turtles are predators that feed on invertebrates. Moreover, jellyfishes and comb jellies can be predators of other cnidar-ians and ctenophores. Sea turtles, especially Dermochelys coriacea, feed on scyphomedusae such as A. aurita. In addition, birds may add scyphozoans to their diets. Some benthic animals like the nudibranchs may feed on the scyphistomae of Cyanea capillata and A. aurita. A single nudibranch can consume as many as...

Ramate In Biology

Philodina aculeata Ehrenberg, 1832, Germany. Measures 0.0138-0.0197 in (350-500 pm). Color may vary from grayish to red or brown. Head has long rostrum and two eyespots. Dorsal side of the trunk has several characteristic large, thornlike spines. The foot has four telescopic retractable pseudo-segments and terminates in four toes. Trophi belong to the ramate type that is characteristic of all bdelloids. A fulcrum is lacking, and the manubria are thin bands that flank the lateral rims of the...

Medusiform sea daisy

Xyloplax medusiformis Baker, Rowe, and Clark, 1986. Body is disc-like, slightly inflated, up to 0.31 in (7.8 mm) body diameter or 0.35 in (9 mm) including peripheral spines. Abacti-nal (dorsal) plates imbricate outwards towards the margin of the body. The peripheral spines are of one size group length 40-75 pm 10-30 mouth frame ossicles present no stomach, instead an oral velum is supported by the mouth frame ossicles. East and west coasts of New Zealand. Found only on sunken wood in deep water...

Turners sea daisy

Xyloplax turnerae Rowe, Baker, and Clark, 1988. Body disc-like, slightly inflated, up to 0.47 in (12 mm) body diameter or 0.54 in (13.6 mm) including marginal spines. Abacti-nal (dorsal) plates imbricate towards centrodorsal plate, marginal spines in two sizes 0.00354-0.00591 in (90-150 pm) and 0.00118-0.0157 in (300-400 pm). A shallow, blind sac-like stomach with a central mouth is present. Tongue of the Ocean, Bahamas, Atlantic Ocean. Attached to wood panels placed in 6,780 ft (2,066 m) for...

Freshwater planarian

Dugesia tigrina (Girard, 1847), New Jersey, United States. Body lanceolate with auricles laterally on head, light to dark brown in color with some forms having a stripe down its midline, light spots on a dark background or dark spots on a light background pharynx large in middle of body, gut with two posterior and one anterior directed branch as others in order. Widespread in North America and has scattered distribution in Europe, where it may have been introduced with aquatic plants. Under...

Distribution

Reproductive Biology

Ctenophores are exclusively marine and can be found in all of the world's oceans, from the poles to the equator and from the surface to as deep as 23,950 ft (7,300 m) in the ocean. It is likely that they occur even deeper, but researchers have not been able to spend much time below this depth. The feeding methods of Pleurobrachia. 1. Hunting with tentacles fully extended 2. When food is snared, the tentacles are retracted 3. Cilia on ctene rows pulsate, allowing the animal to rotate 4. Tentacle...

Systematics of lower Metazoa

Molecular, morphological, and paleontological evidence suggests the most primitive phyla are found within two para-phyletic groups, Parazoa and Radiata. The Parazoa includes two phyla, Porifera and Placozoa, which display the most primitive grade of organization and are at the base of the evolutionary tree. The Radiata contains the radiate phyla, Cnidaria and Ctenophora, the first true metazoans prior to the evolution of the bilateral body plan in the Precambrian. Some enigmatic groups with...

Trichina worm

OTHER COMMON NAMES English Pork worm. Classified as animal mammal parasites and the causal organism of the disease trichinosis, they are small roundworms that live mainly in rats and other small mammals such as pigs that pick up the worm while rooting for food. Adults have a length of 0.055-0.158 in 1.4-4.0 mm , with males measuring 0.055-0.063 in l.4-1.6 mm in length and females 0.118-0.158 in 3.0-4.0 mm in length. Males and females have distinct features. Females possess a uterus and vulva....

Bloody belly

Pleurobrachia Bachei

Lampocteis cruentiventer Harbison, Matsumoto, and Robison, 2001. Also known as Lampoctena sanguineventer. In the order Lobata, but differs from other families by the presence of a deep notch between adjacent subtentacular ctene rows and by the blind aboral ending for all meridional canals. The gut is always a deep red color while the body coloration varies from clear to deep purple and all shades in between . Currently known only from the east coast of the Pacific, however it is believed to...

Order list

Coronatae Order Rhizostomeae Semaeostomeae Stauromedusae Platyhelminthes Phylum Acoela Class Monopisthocotylea Order Polyopisthocotylea Heteronemertea Order Palaeonemertea Nematoda Phylum Adenophorea Class Bursovaginoidea Order Filospermoidea Echinodermata Phylum Crinoidea Class Cephalodiscida Order Rhabdopleurida Chordata Phylum Urochordata Subphylum Ascidiacea Class

Species accounts

Reproductive Biology

The body is large, up to 8 in 200 mm . This species is the typical priapulan. Its body is strongly tubular and ringed with many annulations. The introvert can be quite long when extended, reaching as much as a third of the length of the trunk. At the posterior end are a pair of caudal appendages. Circumpolar Northern Hemisphere to Mediterranean Sea in eastern Atlantic Ocean and California in eastern Pacific Ocean. The hydrostatic skeleton is used for movement. The introvert and anterior part of...

Behavior

Horsehair Worm

Gordiids tend to entangle in large knots during mating. Often, hundreds of individuals can be found in a seemingly Horsehair worm. Photo by A. Captain R. Kulkarni S. Thakur. Reproduced by permission. Horsehair worm. Photo by A. Captain R. Kulkarni S. Thakur. Reproduced by permission. undoable tangle. This behavior has led the gordiids to be called Gordian worms from the Greek myth of Gordius. The behavior of nectonematids has not been studied.

Gamete exchange

Gametes come together in a variety of ways among the animals in the lower metazoan groups. Sperm are generally motile and engage in oocyte-seeking behavior of some sort. The small size and short-term motility of the sperm, however, mean that their efforts are effective for only a very short time thus sperm motility is only effective for meeting the oocyte within very small spaces. Bringing the sperm and oocyte into these small spaces depends on the behavior of the parent animal, which must...

Hermaphrodite Genitalia Images Medical

Hermaphrodite Humans Pictures Medical

Lepidodermella squamata Dujardin, 1841 , River Seine, Paris, France. A short, tenpin-shaped gastrotrich that grows to 0.007 in 0.19 mm in length. Distinct, five-lobed head separated from the body by a short neck. Trunk has posterior caudal furca and two adhesive tubes. Cuticle consists of scales without ridges or spines. Cilia present on the lateral margin of the head and ven-trally in two rows. Freshwater bodies across the United States Arkansas, Ohio, Michigan, New Hampshire, and North...

Sea wasp

Hidradenitis Suppurativa Mortality

Chironex fleckeri Southcutt, 1956, Australia. OTHER COMMON NAMES English Box jelly. Reaches up to 11.8 in 30 cm in diameter, but is difficult to see despite its large size. The as many as 15 tentacles in each corner can reach up to 98.4 ft 30 m distance from the bell. Tropical waters around Australia, from Exmouth, Western Australia, to Bustard Heads, Queensland, as well as around the Indo-west Pacific Ocean near Papua New Guinea, the Philippines, and Vietnam. Full extent of the distribution...

Embryogenesis

The development of a fully functional animal body begins with the transformation of the single-celled zygote into a mul-ticellular embryo. Part of the definition of an animal i.e., a metazoan is that it possesses true multicellularity, which it acquires during the process of embryogenesis. True multi-cellularity is defined not only as the possession of multiple cells in the body, but also a specific division of labor among those cells. In particular, the body of an animal must have somatic body...

Pyrosome

Pyrosoma atlanticum Peron, 1804 , Mediterranean Sea. Individuals called zooids are about 0.33 in 8.5 mm and embedded in a thick, clear tubular test that can reach 23.6 in 60 cm in length. Colonies are pink or yellowish pink. The oral siphons of the zooids are on the outer surface of the tube and the cloacal siphon point to the inside. Water comes in the oral siphon and empties into the common opening inside of the tube. One end is closed and the water exits out a common opening at the other end...

Brittle Star Starfish Anatomy

Brittle Star Anatomy

Ophiuroids range from the poles to the tropics and from intertidal to abyssal plains as well as in deep sea trenches. The deepest recordings were taken from the Bourgainville Trench at 26,270 ft 8,006 m . Brittle and basket star anatomy. Illustration by Patricia Ferrer Brittle and basket star anatomy. Illustration by Patricia Ferrer

Biologyanus Photos

Infected Sea Urchin

Axial gland ampullae esophagus siphon intestine test radial canal ring canal Polian vesicle Aristotle's lantern pharynx Sea urchin and sand dollar anatomy. Illustration by Emily Damstra Grzimek's Animal Life Encyclopedia A toxic sea urchin Tripneustes gratilla covers itself with debris as camouflage. Photo by A. Flowers amp L. Newman Photo Researchers, Inc. Reproduced by permission. A toxic sea urchin Tripneustes gratilla covers itself with debris as camouflage. Photo by A. Flowers amp L....

Orthonectidans

Orthonectids

Phylum Orthonectida Number of families 1 Minute dioecious and dimorphic or hermaphroditic parasites found in tissues of a wide variety of marine invertebrate phyla. Photo A female Rhopalura ophiocomae. Specimens in Nouvel collection, Santa Barbara Museum of Natural History. Photo by Hidetaka Furuya. Reproduced by permission. Phylum Orthonectida Number of families 1 Minute dioecious and dimorphic or hermaphroditic parasites found in tissues of a wide variety of marine invertebrate phyla. Photo A...

Broad fish tapeworm

South American Parasite Fish

Taenia lata Linnaeus, 1758, type locality unknown. OTHER COMMON NAMES German Fischbandwurm. Polyzoic. Strobila with length about 30 ft 9 m there are data about specimens reaching up to 66 ft 20 m , consisting of 3,000-4,000 proglottides. Scolex finger-shaped, with two both-ria. Uterus rosette-shaped in gravid proglottides. Scandinavia, Baltic States, Russia, United States and Canada Great Lakes area, Pacific Coast, Arctic , Ireland, Japan, around some lakes and large rivers in Africa, and South...

Physical factors Light

Aerial View The Great Barrier Reef

Sunlight has an important role in both terrestrial and marine environments, powering the process of photosynthesis that provides energy either directly or indirectly to nearly all forms of life on earth. The diel, or 24-hour cyclical migra tions of epipelagic species, are at least in part active responses to changing light levels. Epipelagic refers to the upper levels of the ocean that are penetrated by enough sunlight for photosynthesis to occur. Aurelia aurita approaches the surface during...

Magnificent urchin

The test diameter can reach 7.8 in 20 cm with brilliant coloration of golden yellow and iridescent blue spots. Spines are long and banded with reddish brown and yellowish white. Areas of test are bare. Tropical coastal waters of the western Atlantic to the northeast South America down to about 295 ft 90 m . Sandy bottoms, shell sand, and limestone outcrops on coral reefs. A fast-moving urchin owing to its ability to walk on its spines. Patchy distribution, but some are known to aggregate. When...

Jaw animals

Phylum Micrognathozoa

Phylum Micrognathozoa Number of families 1 Microscopic animal group with one described species, Limnognathia maerski, characterized by the presence of intracellular plates in the dorsal and lateral epidermis the ventral epidermis is covered with frontal and ventral ciliation ciliophores sensory structures consist of serially arranged tactile bristles the digestive system has a highly complex jaw apparatus, a simple midgut, and a dorsal, periodically functioning anus Illustration Limnognathia...

Outer mesoglea

Lamella Medical Diagram

Medusa. Illustration by Patricia Ferrer Hydroid anatomy. A. Colony B. Medusa. Illustration by Patricia Ferrer and are inappropriately called actinulae, like the juvenile polyps of some Anthomedusae. The Trachymedusae have a bell-shaped umbrella, with circular and radial canals. Gametes ripen on the radial canals. The manubrium is often on a peduncle. The Hydroidomedusa class is represented by a succession of three stages during indirect development. The planula is...

Anemones and corals

Info About Frilled Anemones

Phylum Cnidaria Class Anthozoa Number of families 130 Exclusively polypoid cnidarians. Tubular body with hollow tentacles around the mouth has a pharynx that opens into a digestive cavity subdivided by infoldings of the gut wall. May be solitary or colonial, with or without an internal or external skeleton. Photo Jeweled anenome Corynactis californica Shedd Aquarium. Photo by Patrice Ceisel. Reproduced by permission. Anthozoa is the largest class in the phylum Cnidaria, with over 6,000 extant...

Crownjellyfish

Biological Reproduction

Periphylla periphylla Peron and Lesueur, 1809, equatorial Atlantic Ocean. These medusae have a conical swimming bell that is up to 8 in 20 cm tall and 6.5 in 17 cm in diameter, but specimens from oceanic waters usually are less than 2 in 5 cm in size. The bell of small specimens is transparent and reveals the reddish brown stomach. In large specimens, the bell is opaque and maroon in color. The bell has a pronounced groove with 16 deeply notched lappets beneath it. Twelve thick tentacles emerge...

Oyster leech

Stylochus inimicus Polombi, 1931, Florida, United States. Body is oval or discoid with retractile nuchal tentacles marginal eyes in band, cerebral and tentacular eyes present pharynx long in middle of body, intestinal branches not anastomosing male and female gonopores close to each other in posterior of body. DISTRIBUTION Florida, United States. Under rocks and algae and in oyster shells and other invertebrates. Tends to hide under debris or in shells of oysters and barnacles. Carnivorous...

Thorny headed worms

Thorny Headed Worms

Phylum Acanthocephala Number of families 22 Parasitic thorny headed worms with complex life cycles sexes separated adults found in intestines of vertebrates definitive host , larvae found in hemocoel body cavity of arthropods intermediate hosts and sometimes in body cavities of vertebrates paratenic or transport hosts Photo Scanning electron micrograph of the proboscis of Hypoechinorhynchus thermaceri, taken from the eelpout fish Thermarces andersoni, found near deep sea hydrothermal vents....

Astrids rotifer

Rotifer Reproduction

Encentrum astridae Sorensen, 2001, Bermuda. Measures 0.0121-0.0153 in 308-388 pm . Body is illoricate, elongate, and fusiform. Foot is relatively long and composed of one pseudo-segment, with two closely set parallel-sided toes. Trophi belong to the forceps-like forcipate type that always has relatively slender elements. The species is recognized easily by its very long unci and supramanubria. The species has been recorded from Bermuda and Denmark and probably has a North Atlantic to...

Ascidiacea

Biological Reproduction

Phylum Chordata Class Ascidiacea Number of families 24 Benthic, solitary, and colonial species whose adults are sessile, almost exclusively fixed, firmly attached, or lying free on the sea floor they usually filter feed larvae are free swimming Photo These tunicates Phallusia julinea have a larval stage with notochord, forerunner of the vertebrate spine. Photo by David Hall Photo Researchers, Inc. Reproduced by permission.

Priapulans

Hidradenitis Illustration

Phylum Priapulida Number of families 3 Cylindrical body, the anterior part of which the introvert is covered with chitinous teeth and can be rolled inward at the posterior end are one or two caudal appendages Illustration Tubilucus corallicola. Illustration by John Megahan Phylum Priapulida Number of families 3 Cylindrical body, the anterior part of which the introvert is covered with chitinous teeth and can be rolled inward at the posterior end are one or two caudal appendages Illustration...

Symbiosis and animal parasitism

Scientists estimate that up to 50 of all animal species are parasitic symbionts. Some phyla such as the Platyhelminthes, Nematoda, and Arthropoda contain large a number of parasitic species. Hosts and parasites have coevolved together and under natural conditions many have become mutually tolerant. Host organisms can live independently, but, in most cases, the parasite's association with its host is obligatory. Animal parasites affect the health of humans and domesticated animals throughout the...

Gnathostomulids

Hidradenitis Illustration

Phylum Gnathostomulida Number of families 12 Marine group of microscopic free-living worms characterized by an entirely monociliated epidermis and complex cuticular mouthparts Photo A few species of Filospermoidea, such as this Haplognathia ruberrima, are bright red, while all other gnathostomulids are colorless-opaque. Photo by Wolfgang Sterrer. Reproduced by per- There is no fossil record for this group. Described in 1956 as aberrant Turbellaria flatworms , the gnathostomulids are now...

Slipper sea cucumber

Clark, 1901, Puget Sound, Washington, United States. English Armored sea cucumber, pedal sea cucumber. PHYSICAL CHARACTERISTICS A yellow to pinkish orange and ovoid sea cucumber to 3 in 8 cm long. Both mouth and anus are upturned. The dorsum is arched and covered in large, flat plates. The bottom is a soft, flattened sole with tube feet concentrated around its perimeter and scattered down the center. The 10 white-tipped, red tentacles are extensively branched. In...

Origin of lower Metazoa

Deuterostomes Humans

The lower Metazoa comprises a diverse assemblage of animal phyla traditionally considered primitive by most biologists in the nineteenth and twentieth centuries. Despite claims about their primitive appearance e.g., simple anatomy, small size , the lower Metazoa collectively displays some of the greatest morphological and developmental diversity within the Animalia. There is also mounting evidence to suggest that the primitiveness of many lower metazoans is a secondary phenomenon, i.e., the...

Entoprocts

Emily Damstra

Phylum Entoprocta Kamptozoa Number of families 4 Colonial or solitary tiny benthic animals with a tentacular crown on top, and a slender stalk that attaches basally to the substratum Photo Loxosomella sp. inhabiting parapodia of a polynoid polychaete found at Noto Peninsula, Japan. Photo by Tohru Iseto. Reproduced by per- There has been only one fossil record of Entoprocta, belonging to the extant genus Barentsia, which was collected from the Upper Jurassic of England. The phylogenetic...

Demosponges

Demosponges

Phylum Porifera Class Demospongiae Number of families 80 Soft, elastic, but also tough, friable, or hard, frequently brightly colored sponges varying in shape from encrusting, massive, tubes, or branches to cups or vases the body reinforced by spongin, siliceous containing silica spicules, or a combination of both Photo A row pore rope sponge Aplysina cauli-formis seen near the Cayman Islands. Photo by Andrew J. Martinez Photo Researchers, Inc. Reproduced by permission. The demosponges originated in the Cambrian period and form the largest class of the phylum Porifera, containing about 85 of all described Holocene species. The class Demospongiae is divided into three subclasses 1. Subclass Homoscleromorpha, with one order, Ho-mosclerophorida one family and about 60 species. 2. Subclass Tetractinomorpha, with four orders, Astrophorida also known as Choristida , Chon-drosida, Hadromerida, and Spirophorida 22 families and several hundred species. 3. Subclass Ceractinomorpha, with nine...

Mushroom coral

Coral Biology

Fungia scutaria Lamarck, 1801, no locality given. OTHER COMMON NAMES English Plate coral German Pilzkoralle, Rasiermesserkoralle Hawaiian ko'a-kohe Solitary and free-living unattached as an adult oval to elongate skeleton from 1-7 in 2.5-18 cm long resembles the underside of a toadstool mushroom numerous small tentacles I Goniastrea aspera I Fungia scutaria arise from lobes formed by underlying skeleton. Usually brown with irregular pink or violet patches tentacular lobes often bright green....

Candy cane sea cucumber

Sea Cucumber The Solomon Islands

Thelenota rubralineata Massin and Lane, 1991, Madang, Papua New Guinea. H Molpadia oolitica H Chiridota hydrothermica H Thelenota rubralineata A large and colorful sea cucumber to 20 in 51 cm long and trapezoidal in cross section, the candy cane sea cucumber has a pronounced, flattened ventral sole crowded with tube feet. The dorsal side bears numerous large, pointed papillae. The candy cane sea cucumber has a unique crimson herringbone-like pattern of stripes on a white background and bears...

Defensive behavior

Sea Stars Behavior

Defensive behavior represents a class of behavior referred to as communication behavior. Metazoans must defend themselves against an impressive array of predators. To survive against an attack, various strategies have evolved. These Forbes' common sea star Asteruas firbesii regenerating arms that have been lost. This ability is a type of defense mechanism, enabling the sea star to stay alive even if a predator takes an arm. Photo by Andrew J. Martinez Photo Researchers, Inc. Reproduced by...

Contributors to the first edition

The following individuals contributed chapters to the original edition of Grzimek's Animal Life Encyclopedia, which was edited by Dr. Bernhard Grzimek, Professor, Justus Liebig University of Giessen, Germany Director, Frankfurt Zoological Garden, Germany and Trustee, Tanzanian National Parks, Tanzania. Dr. Michael Abs Curator, Ruhr University Bochum, Germany Bombay Natural History Society Bombay, India Dr. Rudolph Altevogt Professor, Zoological Institute, University of M nster M nster, Germany...

Smalltail lancelet

Branchiostoma Belcheri

Branchiostoma belcheri Gray, 1847, Borneo. Possibly three subspecies B. belcheri belcheri, B. belcheri japonicus, B. belcheri tsing-tauense. 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. Sixty-five 61-69 myotomes 38 34-43...

By the wind sailor

Hydroid the colony is a flattened oval to slightly S-shaped float, with a triangular sail and concentric air chambers up to 1.5 in 40 mm long and 0.78 in 20 mm wide, higher in the center than at the edges. Float and sail are supported by chitin covered by mantle tissue margin of float is soft and flexible. The center of colony underside is a single large gastrozooid encircled by a ring of medusa-producing gastro-gonozooids and a peripheral band of dactylozooids. Central-feeding zooid oval, with...

Behavioral characteristics of invertebrates

Haliclystus Aricular Stalked Jellyfish

This chapter will familiarize you with issues and examples related to the behavior of invertebrates. The large number and sheer diversity of invertebrates requires a restriction in the types of behaviors and species that can be discussed. The behaviors selected were based in part on their importance to the survival of an individual organism. Since there is little known about the behavior of many of the lower invertebrate and deuterstome phyla, examples of insects and other protostomes were used...

Learned behavior

Learned behavior is another class of behavior exhibited by invertebrates. The reasons for studying learning in invertebrates are varied and include gaining further knowledge of how biochemistry and physiology affect the process of learn ing, searching for similarities and differences within and between phyla, and using learning paradigms to explore applied and basic research questions e.g., how pesticides influence the foraging behavior of the honey bee . The term learning, like the term...

Wheel wearers

Wheel Reproductive System

Phylum Cycliophora Number of families 1 Microscopic acoelomate animal group living as commensals on the mouthparts of the Norway lobster Nephrops norvegicus characterized by a highly complex life cycle with six life stages the dispersal stage is the chordoid larva Illustration Symbionpandora. Illustration by Bruce Worden Phylum Cycliophora Number of families 1 Microscopic acoelomate animal group living as commensals on the mouthparts of the Norway lobster Nephrops norvegicus characterized by a...

Direction of movement

Crinoid Illustration

Three groups of arms red, yellow, blue move separately to achieve forward motion. Illustration by Emily Damstra sibly facilitating the capture of food particles by the tube feet. Sea lilies assume a similar feeding posture, although they recurve their arms almost 270 upstream to form a parabolic filtration fan. The mouth may be oriented laterally downstream, with the food grooves also turned downstream, or it may be oriented upward in slack currents. Feather stars...

Sea stars

Anatomy Pisaster Ochraceus

The class Asteroidea is a highly diverse group comprised of seven orders, 35 families, and an estimated 1,600 known living species, although their precise phylogenetic relationship and hence classification still proves challenging to taxonomists. Asteroids belong to a major group of other bottom-dwelling animals called echinoderms. Collectively this group includes echinoids sea urchins , holothurians sea cucumbers , crinoids feather stars , and ophiuriods brittle stars , the latter group...

Girdle wearers

Pliciloricus

Loricifera is traditionally considered a phylum in the group Introverta. The closest relatives of the loriciferans are the Kinorhyncha kinorhynchs and Priapulida priapulans . Loricifera includes 11 described species as of 2003. All species have been assigned to one order named Nanaloricida that includes two families, the Nanaloricidae and the Pliciloricidae. As of 2003, more than 100 species have been collected that have not yet been described. Adult loriciferans range in size from 0.008 to...

Calcareous sponges

Sponge Anatomy

Phylum Porifera Class Calcarea Number of families 22 Marine sponges with calcareous skeletal elements spicules Photo A calcareous sponge in a cryptic reef environment in waters near the Little Cayman Islands, at a depth of 82 ft 25 m . Photo by Gregory G. Dimijian, M. D. Photo Researchers, Inc. Reproduced by permission. The fossil record of unambiguously identified Calcarea is relatively poor and fragmented. Most calcareous sponges in the fossil record were classified as either stromatoporoids,...

Sea lilies and feather stars

Reproduction Sea Lilies

Phylum Echinodermata Class Crinoidea Number of families 25 Stalked or stalkless organisms with a crown composed of a calyx, five or multiple arms, an anal cone, and a mouth pointing upward Photo Feather star arms trapping plankton near Sipadan Island, Borneo, in the South China Sea. Photo by Jeff Rotman Photo Researchers, Inc. Reproduced by permission. Crinoids are a living lineage of echinoderms more than 500 million years old. The first crinoids were stalked forms the sea lilies , whose...

Symbiosis and modern biology

The recognition of symbiotic relationships has had a revolutionary impact on modern biological thought. The idea that mitochondria and chloroplasts are transformed by symbiotic bacteria provides a common thread to the biological world and raises hope of finding other symbiotic wonders among life's diversity. Plants and animals have acquired new metabolic capabilities through symbioses with bacteria and fungi. Mammalian herbivores and termites digest cellulose with the help of microbial...

Northern basket star

Gorgonocephalus arcticus Leach, 1819. OTHER COMMON NAMES German Gorgonenhaupt Norwegian Medusahode. PHYSICAL CHARACTERISTICS A large basket star with a disk 4.01 in 102 mm in diameter, with highly branched long 14.1 in or 360 mm arms. The disk is pentagonal and bare, leathery with five pairs of ridges radiating from the center to the sides of the arms. The five sturdy arms divide into two branches near the disk and then redivide equally five or more times. The arm joints have short hooked...

Rhombozoans

Phylum Rhombozoa

The phylum Rhombozoa includes three families, eight genera, and approximately 150 species. The three families are Conocyemidae, Dicyemidae, and Kantharellidae. Edouard van Beneden proposed the name Mesozoa for these organisms as an intermediate between Protozoa and Metazoa in body organization. Later zoologists considered rhombozoans degenerated from metazoans such as trematodes because of adaptation for the parasitic lifestyle. Results of phylogenetic studies with nucleotide sequences of 18S...

Portuguese man of war

Holothuria physalis Linn , 1758, Atlantic Ocean. OTHER COMMON NAMES English Blue bottle French Gal re, fr gate, vaisseau de guerre hollandais, vaisseau de guerre portugais. The only pleustonic siphonophore. Colonies consist of a large, purplish blue horizontal pneumatophore that floats on the sea surface, reaching 11.8 in 30 cm in length in the largest specimens pneumatophore carries the polyps, which form cormidia at the oral end at its top, an erectile, longitudinal crest or sail that may be...

Resources

EA Field Guide to the Shallow-water Echinoderms of the British Isles. London Immel Publishing Ltd., 1993. Sloan, N. A., and A. C. Campbell. Perception of Food. In Echinoderm Nutrition, edited by Michael Jangoux and John Lawrence. Rotterdam, Netherlands A. A. Balkema, 1982. Blake, B. D. Adaptive Zones of the Class Asteroidea Echinodermata . Bulletin of Marine Science 46 1990 701-718. -. A Classification and Phylogeny of Post-Paleozoic Sea Stars Asteroidea Echinodermata . Journal of...

Turbellarians And Thigmotaxis

Phylum Platyhelminthes

Turbellarians display a number of behaviors that prevent them from straying beyond their normal habitats and allows to them to maintain orientation within those habitats. For instance, most turbellarians are positively thigmotactic touch ventrally and negatively thigmotactic dorsally. This allows them to maintain their ventral side against the substrate in benthic forms. In other species where touch may not be the best way to orient to a substrate such as interstitial and pelagic A colorful...

Nightlight jellyfish

Lappet Pelagia

Pelagia noctiluca Forskal, 1775, Mediterranean Sea. I Aurelia aurita I Pelagia noctiluca OTHER COMMON NAMES English Mauve baubler. The swimming bell usually is less than 3.5 in 9 cm in diameter. It has a bumpy surface from clusters of stinging cells, which impart a purple or yellowish color to the translucent bell. There are four elongate oral arms and eight long tentacles that alternate with eight rhopalia in the clefts between lappets. There is no polyp stage. The medusa is found in tropical...

Ectoderm

Ectoderm Gonads

Polyp. Illustration by Patricia Ferrer down to shallow subtidal depths, usually attached to benthic plants algae or sea grasses . One species is known from deep hydrothermal vent communities. Coronate medusae typically are found at mesopelagic depths 1,625-4,875 ft, or 500-1,500 m , but a few species occur near the surface. Deep-living species may have polyps at abyssal depths, but the polyps of shallow-living species are on shallow substrates. Semaeostome and...

Placozoans

How Phylum Placozoa Feed

Phylum Placozoa includes only one species, Trichoplax adhaerens. Because this phylum is so small, it has no classes or orders assigned to it. There is one family, the Trichoplacidae. Little is known about this organism because it has never been observed in the wild it has been studied from samples cultured in laboratory aquaria around the world. Trichoplax ad-haerens was first discovered in the aquarium of the Graz Zoological Institute in Austria in 1883. A second species, Trichoplax reptans,...

Phylum summaries

Brief summaries of the primary reproductive and developmental strategies of each lower metazoan and deuterostome phyla follow. The variations are within each phylum are great, however, and the short summaries below are intended only to situate each phylum within the overall context of reproductive strategies and processes discussed earlier. Interested readers should consult the references listed for further details and analyses. The limited information on Trichoplax adhaerens, the only known...

Habitat conservation

Mangroves Keys

Organisms have evolved to live in certain habitats. It stands to reason, then, that the most severe problem in protecting global biodiversity concerns habitat destruction and fragmentation. Habitats are generally defined by myriad physical parameters like temperature, rainfall, elevation, topography, salinity, soil type and many others. For tuna, habitat might be generally defined as the pelagic ocean within a certain temperature range. For tiny tardigrades, or moss bears, habitat may be forest...

Orientation behavior

Common Sea Urchin

Over the years various classification systems have been developed to describe orientation, and the terminology used within these systems is confusing. Popular systems in which orientation can be described are kinesis and taxis. Orientation behavior represents an example of the type of behavior referred to as maintenance behavior. The simplest response through which invertebrates find a suitable location to live is referred to as kinesis. The response is not directed toward or away from a...