Classes of Echinoderms: Crinoidea

Questions and Answers

What is the defining feature of Class Crinoidea?

They prey on oysters and clams.

They can release their digestive organs for protection.

They have long, narrow arms.

They are sessile as adults. (correct)

How many species are there in Class Ophiuroidea?

2000

What is a characteristic feature of sea urchins in Class Echinoidea?

They have flat, round shapes.

They have 5 teeth that surround their mouth. (correct)

They use tube feet to capture food. (correct)

They live in coral reefs.

What type of environment do sea cucumbers from Class Holothuroidea inhabit?

Soft sediment on the sea bottom Signup and view all the answers

Which of the following classes do sea stars belong to?

Class Asteroidea Signup and view all the answers

What is a unique behavior of the Class Holothuroidea?

Evisceration Signup and view all the answers

Study Notes

Class Crinoidea - The Crinoids

Comprises sea lilies and feather stars, known for their sessile adult stage.
Adults attach to rocks or the ocean floor using a long stalk.
Possess five main arms that can branch out to form up to 200 additional arms.
Have sticky tube feet at the arm's end for filtering small organisms and aiding in respiration.
Unique morphology: mouth faces upward, contrasting with other echinoderms.

Class Ophiuroidea

Largest echinoderm class, featuring around 2,000 species of basket stars and brittle stars.
Characterized by long, narrow arms enabling faster movement compared to other echinoderms.
Primarily inhabit ocean floors, often found under stones or within crevices in coral reefs.

Class Echinoidea

Includes approximately 900 species like sea urchins and sand dollars.
Sea urchins adapted to hard sea bottoms utilize tube feet for movement and possess five teeth surrounding their mouth for scraping algae.
Sand dollars inhabit sandy coastal areas, using tube feet to collect food settling around their bodies.

Class Holothuroidea

Comprises sea cucumbers, notable for their armless structure.
These echinoderms live on the sea bottom, crawling or burrowing into soft sediments.
Feature modified tube feet that form tentacles around their mouth to sweep food closer.
Unique defensive behavior: capable of evisceration, releasing digestive organs for protection.

Class Asteroidea

Known as sea stars, this group is distributed in coastal waters worldwide.
Exhibit a variety of colors and shapes.
Economically significant as they prey on oysters, clams, and other commercially valuable organisms.

Description

Explore the fascinating world of Crinoidea, known as the crinoids, which includes sea lilies and feather stars. Learn about their unique structure, feeding mechanisms, and their role in marine ecosystems. This quiz will test your knowledge on these intriguing echinoderms.