Fragile brittle star

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Fragile brittle star
Fragile brittle star (Ophiothrix fragilis), Strangford Lough, Northern Ireland

Fragile brittle star ( Ophiothrix fragilis ), Strangford Lough, Northern Ireland

Systematics
Class : Brittle stars (Ophiuroidea)
Order : Ophiurida
Subordination : Chilophiurina
Family : Ophiothricidae
Genre : Ophiothrix
Type : Fragile brittle star
Scientific name
Ophiothrix fragilis
( Abildgaard in OV Müller , 1789)

The fragile brittle star ( Ophiothrix fragilis ) is a brittle star of the species Ophiothrix in the family Ophiothricidae and order Ophiurida that in the eastern Atlantic Ocean is widespread.

features

The body disc reaches a diameter of up to 2 cm, the five arms five times the body disc diameter. The color varies widely from dark purple to white, yellowish, orange or reddish, often with red spots, with the arms mostly white or gray with red stripes. With the exception of the conspicuous bare radial shields, the top of the body disc is covered with short or longer spines. The underside of the body disc is covered with short spines, with the exception of the proximal part. The dorsal arm plates are bare and have a more or less distinct longitudinal keel. The ventral arm plates are approximately rectangular with a small proximal depression and a slightly concave outer edge. There are generally 7 pairs of upright and often toothed arm spines per segment. The openings for the suction feet are partially covered by a small tentacle scale. On the top of the jaw are a group of dental papillae and a vertical row of broad teeth, but there are no oral papillae. There are two pairs of suction cups in the mouth.

distribution

Ophiothrix fragilis is in the eastern Atlantic Ocean from the Lofoten , Iceland and Norway over the entire west coast of Africa to the Cape of Good Hope , to the Azores , in the Mediterranean and on all coasts of the North Sea spreads

The fragile brittle star prefers hard substrates, but also sand and can often be found in empty bowls or under stones from the shore to a depth of 350 m.

Development cycle

Ophiothrix fragilis is sexually separated and is around 5 to 10 years old. It reaches sexual maturity at around 6 to 10 months, and in the months from June to October males and females come together, both of which release their gametes into the open sea water so that external fertilization takes place. Free-swimming larvae develop from the zygotes , sink after 11 to 30 days and metamorphose into small brittle stars .

Way of life

The fragile brittle star scavengers and feeds on a number of dead organisms. In addition, as a filter feeder with raised arms and outstretched suction feet , it is able to fish particles of detritus from the seawater flowing past, which are brought to the mouth with the arms.

literature

  • John Barrett, CM Young: Collins Pocket Guide to the Sea Shore. Collins, London 1958. p. 180.
  • John D. Fish, Susan Fish: A Student's Guide to the Seashore . Cambridge University Press, Cambridge 2011. 540 pages. Ophiothrix fragilis , p. 376.
  • GF Warner, JD Woodley (1975): Suspension feeding in the brittle star Ophiothrix fragilis. Journal of the Marine Biological Association of the United Kingdom 55, pp. 199-210.

Web links

Commons : Fragile brittle star ( Ophiothrix fragilis )  - Collection of images, videos and audio files