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Gorgonocephalus eucnemis

(Basket Sea Star)

Overview

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Interesting Facts

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Common Names

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Common Names in English:

Basket Sea Star, Basket Star

Description

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Physical Description

Species Gorgonocephalus eucnemis

Unlike any other local ophiuroid, the rays of the basket star branch repeatedly dichotomously. The central disk is covered with a loose-fitting skin with a dark brown color between the bases of the rays and a pinkish color, more similar to the ray color, near the ray bases. Actual color may be variable from tan, beige, orange-red, and pink to almost white; but the central disk is usually darker than the rays.[1]

Size/Age/Growth

One of the largest known ophiuroids, it can have a diameter of up to half a meter.[1]

Habitat

Usually on rocky bottoms with moderate to strong currents . Sometimes on sandy or muddy bottoms which have projecting boulders , sea fans, or sea pens.

We most frequently observe this basket star on rocky bottoms, in areas of high current, and on an elevated place such as the top of a boulder or underwater hillock where it is fully exposed to the current.[1]

Depth Range : Subtidal , 10 m to nearly 2000 m, most commonly 15-150 m. [1]

Biome: Marine .

Ecology: This species seems to have a strong co-occurrence with the soft coral Gersemia rubiformis. In Puget Sound , Gorgonocephalus juveniles have been reported within the pharynges of Gersemia polyps, where they appear to develop and apparently feed . The young do not leave the Gersemia until their rays are long enough to capture food.[1]

Biology

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Diet

It feeds on suspended particles by spreading its rays out like a fan, oriented mostly perpendicular to the current . Macroscopic zooplankton such as copepods , chaetognaths , and jellyfish are caught by microscopic hooks on the rays. The fine branchlet tips (see picture) then curl around the object and slowly move it toward the mouth (exact method is unclear). The prey of basket star species is said to range up to 3 cm (just over an inch ) in size, and most basket stars capture prey mainly at night but may retain their prey until daytime to actually feed on them. Mucus may also help to immobilize prey. This species has also been reported to feed on the small benthic sea pen Stylatula elongata.[1]

Reproduction

This species seems to have a strong co-occurrence with the soft coral Gersemia rubiformis. In Puget Sound , Gorgonocephalus juveniles have been reported within the pharynges of Gersemia polyps, where they appear to develop and apparently feed . The young do not leave the Gersemia until their rays are long enough to capture food.

Behavior

Most common on rocky bottoms , in areas of high current , and on an elevated place such as the top of a boulder or underwater hillock where it is fully exposed to the current. The species is highly active , writhing its rays in all directions like an animated bush . It almost always has the tips of the rays curled into tiny loops for catching prey .

Taxonomy

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Synonyms

Gorgonocephalus caryi Lyman • Gorgonocephalus japonicus Doederlein

Notes

Name Status: Accepted Name .

Comment: Distribution: Juveniles are known to live on, or in, the polyps of alvyonarians (Patent , 1970) Authority: (J. Müller & Troschel, 1842)

Last scrutiny: 18-Jul-2007

Similar Species

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Members of the genus Gorgonocephalus

ZipcodeZoo has pages for 2 species and subspecies in this genus:

G. arcticus (Northern Basket Star) · G. eucnemis (Basket Sea Star)

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal February 01, 2008:

Identifiers

Footnotes

  1. Cowles, Dave. Key to Invertebrates Found At or Near The Rosario Beach Marine Laboratory (a campus of Walla Walla University) Fidalgo Island, Anacortes, WA May 2009. [back]
Last Revised: 2014-04-23