Starlet sea anemone

Nematostella vectensis

Nematostella vectensis is a sea anemone that occurs in the North Atlantic and has become in recent years become a model organism for the study of the origin of the complexity of animal blueprints.

Features

Nematostella vectensis is a small elongated anemone 12 to 20, standing in the normal case 16 in two circles around the mouth opening tentacles. The outer circle is longer and usually has outward and downward, while the tentacles of the inner circle are stretched upward. All tentacles are at the base somewhat thickened, then run but long and thin to a slightly extended tip. They are colorless with pale tips and white stripes at irregular intervals. The mouth is sitting on a slightly conical elevation.

The hull is externally whitish to pale gray, the translucent mesentery are dependent on the food, pale pink, green, brown or blackish. In the extended state of the body about four to six times as long as broad, smooth and translucent, and usually accomplished in the field, a length 10 to 15 millimeters. Especially in laboratory animals can, however, with up to six centimeters in length is also substantially greater. In the contracted state of the hull is only about twice as long as wide and appears wrinkled and opaque. Externally, the hull is divided into three sections, which, however, not particularly stand out clearly from each other. The capitulum is only a short translucent section. The scape has just below the tentacles on a ring of cream-colored markings, follow a translucent band and then another series of cream-colored spots, which run down the trunk and fade it. The Physa is in the extended state a translucent bubbles through which the septa are clearly visible. You can partially fed, but do not be completely invaginated into the scape.

Occurrence

The species is known from the south-east coasts of Great Britain and the Atlantic and Pacific coasts of North America, where it occurs in each individual populations at suitable locations. Due to the scattered distribution in partially threatened by pollution habitats it is in the Red List of the International Union for Conservation of Nature and Natural Resources (IUCN ) listed as threatened ( Vulnerable ).

Way of life

Nematostella vectensis populated fine-grained mud surfaces at the edges of tidal creeks in salt marshes and brackish ponds. They are usually buried up to the top of the fuselage with the tentacles. Occasionally, they are also open or are attached to seagrasses. They can tolerate relatively large fluctuations in salinity and temperature.