No common name

Spadella cephaloptera

ORDER

Phragmphora

FAMILY

Spadelliidae

TAXONOMY

Sagitta cephaloptera Busch, 1851 Northeast Atlantic, Orkney Islands.

OTHER COMMON NAMES

None known.

PHYSICAL CHARACTERISTICS

Individuals have 7-10 hooks, 3-5 anterior teeth, and 2-4 posterior teeth. Maximum adult body length is 0.22 in (5.5 mm), and the relative tail length is 49-58% of total body size. The body is firm, broad, and opaque. Transversal muscles are present in the trunk. A pair of short lateral fins is located almost entirely on the tail segment and is connected to the tail fin by rays. The species has a collarette, small gut diverticula, and a prominent head. Eyes contain pigment spots. Seminal vesicles are oval or rounded, touching both the tail fin and lateral fins. Ovaries are short and broad. The ova are large and are sometimes loose in the trunk cavity. There are glands and adhesive papillae on the ventral side of the tail.

DISTRIBUTION

Neritic and benthic. Occurs between 0 and 82 ft (0-25 m), from about 40°N to 40°S.

HABITAT

Adheres to objects such as rocks or sea grass in benthic coastal areas. It can swim for short distances.

BEHAVIOR

Lives in benthic coastal layers. Benthic species are the only chaetognatha that can be observed in aquariums for long periods of time. Observations about behavior are known from these benthic species.

FEEDING ECOLOGY AND DIET Prefers small copepods.

REPRODUCTIVE BIOLOGY

Two mature individuals with full seminal vesicles maneuver close to each other to mate. One will deposit a sperm package or spermatophore on the dorsal neck region of the other individual. Then the sperm moves toward the genital opening and is stored until eggs are mature. The eggs are fertilized internally and then released into the water.

CONSERVATION STATUS Not listed by the IUCN.

SIGNIFICANCE TO HUMANS None known. ♦

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


Post a comment