What is the definition of Echinoid in biology?

What is the definition of Echinoid in biology?

echinoid. / (ɪˈkaɪnɔɪd, ˈɛkə-) / noun. any of the echinoderms constituting the class Echinoidea, typically having a rigid ovoid body. The class includes the sea urchins and sand dollars.

What phylum is an Echinoid?

Echinoderm
Sea urchins/Phylum

What is crinoid biology?

Crinoids are echinoderms found in both shallow water and at depths to 9000 m. They may be free living as adults or connected to the substratum by a stalk (sea lilies) or without a stalk (feather stars).

What is Ophiuroid in biology?

Definition of Ophiuroidea: class of echinoderms commonly known as brittle stars, having a star-shaped body with the arms clearly marked off from the central disc.

What is a regular echinoid?

Regular echinoids have no front or back end and can move in any direction. Irregular echinoids have a definite front and back and do move in a particular direction. This is because regulars and irregulars have very different ways of life.

What is the skeleton of an Echinoid called?

Like all echinoderms, echinoids have a skeleton composed of calcitic plates embedded in their skin (their skeleton is internal, like ours). This skeleton has a very particular structure, termed stereom. In almost all groups of echinoid the plates are firmly bound together to form a solid skeleton, called the test.

What are examples of crinoids?

Comatulida
ArticulataInadunataFlexibilia
Crinoids/Lower classifications

What is the origin of the word echinoid?

Origin of echinoid. echin(o)- + -oid. any of a class (Echinoidea) of echinoderms, including the sea urchins and sand dollars.

What is the classification of echinoderms?

An echinoderm of the class Echinoidea, which includes the sand dollars and sea urchins. THE AMERICAN HERITAGE® DICTIONARY OF THE ENGLISH LANGUAGE, FIFTH EDITION by the Editors of the American Heritage Dictionaries.

What does a typical echinoid spine look like?

A typical regular echinoid spine (Phalacrocidaris merceyi). Spines vary greatly between species; some are needle-like, others club-like, some are poisonous and others possess thorny barbs. It is often easier to identify a species by its spines as opposed to its test, as they are much more variable and distinctive.

What is the classification of a sea urchin?

echinoid of or like a sea urchin any of a class (Echinoidea) of echinoderms, including the sea urchins and sand dollars An echinoderm of the class Echinoidea, which includes the sand dollars and sea urchins.