Echinodermata Phylum Flashcards

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Questions and Answers

Which of the following organisms fall within the phylum Echinodermata? (Select all that apply)

Sea cucumbers (correct)

Sea urchins (correct)

Sea lilies (correct)

Sea stars (correct)

What kind of environment do echinoderms live in?

Marine

How old is this lineage?

About 600 mybp

The number of extant species of echinoderms is _ and extinct species is _

6500, 13000 Signup and view all the answers

What keeps echinoderms isolated to only marine environments?

They cannot osmoregulate Signup and view all the answers

What is the endoskeleton of echinoderms made of?

CaCO3 Signup and view all the answers

What are the individual plates of calcium carbonate called?

Ossicles Signup and view all the answers

What happens when ossicles fuse together?

They form a test Signup and view all the answers

What does it mean to have a true coelom?

This means that the internal cavity and all the organs are lined with mesoderm. Signup and view all the answers

What does it mean to be a deuterostome?

This means that the fate of the blastopore is to become the anus. Signup and view all the answers

What are the class names of the 5 major extant species of echinoderms? (Select all that apply)

Echinoidea Signup and view all the answers

What class is considered the out-group to the echinoderms?

Crinoidea Signup and view all the answers

Although echinoderms are considered bilateral animals, what type of symmetry do they have?

Secondary pentaradial symmetry Signup and view all the answers

The is oriented up. The is oriented down.

anus, mouth Signup and view all the answers

What is the axis of symmetry known as and why is it called this?

Oral-aboral axis. This is because the axis runs from the mouth to the anus. Signup and view all the answers

What is the water vascular system?

This is a subdivision of the coelom that is used for eating, locomotion, reproduction, and excretion. Signup and view all the answers

Through what sieve-like structure does the water vascular system get water?

Madreporite Signup and view all the answers

Through what structure is the madreporite connected to the ring canal?

Stone canal Signup and view all the answers

What structure is squeezed in order for the tube feet to extend?

Ampulla Signup and view all the answers

Explain the reproduction of echinoderms.

They perform sexual reproduction with separate sexes and most release gametes into the water through external fertilization. Asexual reproduction occurs when limbs are removed and 20% of the disk is still present. Signup and view all the answers

How do these organisms affect ecology?

They are food to some and can potentially decimate protected coral reefs. Signup and view all the answers

What is the larvae of these organisms called?

Triarch larvae Signup and view all the answers

Class: Asteroidea - What organisms fall into this class? (Select all that apply)

Sea stars Signup and view all the answers

How many known species are within the class Asteroidea?

About 1500 species Signup and view all the answers

What do organisms in the Asteroidea class prefer to feed on?

Mollusks Signup and view all the answers

How can you tell organisms from the Asteroidea class from other 'star-like' relatives?

The arms of Asteroidea are broadly attached to their central disk while many other relatives have very skinny arms at the base of the central disk. Signup and view all the answers

How do organisms in the Asteroidea class digest their food?

They protrude their stomachs and digest the organisms externally. Signup and view all the answers

Where can you find the gonads in a sea star dissection?

They lie between the digestive glands and ampulla. Signup and view all the answers

What are papulae and where are they located?

They are skin gills and are located on the surface of the sea star. Signup and view all the answers

What are pedicellariae and where are they located?

They are claws used for cleaning the surface of the organism. They are located on the surface of the sea star. Signup and view all the answers

Explain the nervous system of the Asteroidea class.

They have a loose net of nerves that includes radial nerves in the arms and a nerve ring in the central disk. These organisms cannot see, but they can detect light. Signup and view all the answers

Class: Echinoidea - What organisms fall into this class? (Select all that apply)

Sand dollars Signup and view all the answers

Study Notes

Echinodermata Overview

Includes sea stars, sea urchins, sea lilies, and sea cucumbers.
Exclusively marine organisms, unable to osmoregulate.

Evolutionary History

Lineage dates back approximately 600 million years.
Extant species count around 6,500; extinct species total about 13,000.

Body Structure

Endoskeleton composed of calcium carbonate (CaCO3).
Individual plates are called ossicles; when fused, they form a test.
Possess a true coelom, meaning internal cavities and organs are lined with mesoderm.

Development and Symmetry

As deuterostomes, the blastopore develops into the anus, leading to the anus forming before the mouth.
Exhibit secondary pentaradial symmetry, reflecting five axes of symmetry.

Morphological Orientation

The oral-aboral axis extends from mouth (down) to anus (up).

Water Vascular System

A subdivision of the coelom used for locomotion, feeding, reproduction, and excretion.
Water enters the system through a sieve-like structure known as the madreporite.
The madreporite connects to the ring canal via the stone canal.
Extension of tube feet is facilitated by squeezing the ampulla.

Reproductive Methods

Primarily reproduce sexually with separate sexes, often via external fertilization.
Asexual reproduction occurs when limbs are removed, provided 20% of the central disk remains.

Ecological Impact

Echinoderms serve as food sources for various marine species.
Certain species, like the Crown of Thorns sea star, can significantly damage coral reefs.

Larval Stage

Larvae referred to as triarch larvae, indicative of their early developmental form.

Class: Asteroidea (Sea Stars)

Approximately 1,500 known species.
Prefer to feed on mollusks.
Distinctive arms are broadly attached to the central disk, differing from other star-like relatives with narrower bases.
Digestion involves externally protruding their stomachs to digest prey.
Gonads located between digestive glands and ampulla.
Papulae function as skin gills on the sea star's surface.
Pedicellariae act as cleaning claws, also situated on the surface.
Nervous system consists of a loose net with radial nerves and a nerve ring; can detect light but not see.

Class: Echinoidea (Sea Urchins, Sand Dollars, and Sea Biscuits)

Not detailed in the provided text but is part of the broader Echinodermata phylum.

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Description

Explore the fascinating world of Echinodermata with these flashcards. Test your knowledge on various organisms, their environments, and their evolutionary history. Perfect for students studying marine biology or anyone interested in marine life.