Ophiuroidea

The ophiures ( Ophiuroidea ) are echinodermatous close to the asteries (or starfishes). They were nourissent mainly of young people Mollusques and Annélides. Their cinqs arm is fine, the central disc is well individualized and they do not have an anus (rejection by the mouth).

Morphology and anatomy

The ophiures are one of the five classes of echinodermatous S, characterized by a body discoïdal flattened lower face, whose five arms completely independent of the body leave, which distinguishes them from the Astérie S (starfishes).

The arms of ophiure are hails, with round section, very long compared to the body and likely of undulating and fast movements. Their axis is composed of a great number of small discs limestones, called vertebrae, articulated between them and joined together by flexible ligaments and muscles. They are covered with scales and often carry prickles; they are equipped with rudimentary feet, which are not used for the locomotion.

All the central internal organs are contained in the body discoïdal. The digestive type has a loop in the center of the ventral face, a large stomach, but not of anus. It does not have any gland going in the arms, as it is the case of the asteries. Around the esophagus is a nervous collar which sends a central nerve in each arm. A network of vessels contains a liquid similar to sea water, with some globules amiboïdes.

The majority of ophiures answer the type which has just been described, but there exists a small section, of very different aspect, the euryales , characterized by their ramified arms.

Reproduction

The genital glands open in pockets located, with the number of a pair, the base of each of the five arms.

These ten pockets pockets can at certain species be used for incubation of the young people.

The ophiures give eggs which produce pelagic larvae, to structure and complicated, known metamorphoses under the name of ophiopluteus . When the young ophiure is sufficiently developed, the larva falls on the bottom, disaggregates, and thus puts in freedom the animal.

Ecology

The ophiures all are marine, and all crawl on the bottom, from the littoral in the great depths. One found some up to 4000 Mr. It exists about it in all the seas.

Place des ophiures in the animal kingdom

List orders

order Oegophiurida

sub-order Zeugophiurina

family Ophiocanopidae

order Ophiurida Müller and Troschel, 1840

sub-order Chilophiurina Matsumoto, 1915

family Ophiocomidae Ljungman, 1867
family Ophiodermatidae Ljungman, 1867
family Ophioleucidae
family Ophionereididae Ljungman, 1867
family Ophiuridae Lyman, 1865

sub-order Gnathophiurina Matsumoto, 1915

family Amphilepididae Matsumoto, 1915
family Amphiuridae Ljungman, 1867
family Ophiactidae Matsumoto, 1915
family Ophiothricidae Ljungman, 1866

sub-order Laemophiurina Matsumoto, 1915

family Hemieuryalidae
family Ophiacanthidae Perrier, 1891

order Phrynophiurida Matsumoto, 1915

sub-order Ophiomyxina Fell, 1962

family Ophiomyxidae Ljungman, 1866

sub-order Euryalina Lamarck, 1816

family Asteronychidae Müller and Troschel, 1842
family Asteroschematidae Verrill, 1899
family Euryalidae
family Gorgonocephalidae Ljungman, 1867

External references

Simple: Brittle star

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