Echinodermata Flashcards

Questions and Answers

Identify 4 general examples of echinoderms.

Sea stars, sand dollars, sea urchins, sea cucumbers

Differentiate the symmetry of adult echinoderms from that of their larvae stage.

Adults are radially symmetrical; larvae are bilaterally symmetrical

Were early echinoderms able to move as adults?

False

Because of adults being sessile, what evolved as a result?

Radial symmetry Signup and view all the answers

How many species of echinoderms are still sessile?

80 Signup and view all the answers

What characteristic makes echinoderms different from all other invertebrates?

They are deuterostomes Signup and view all the answers

Are echinoderms more closely related to us or other invertebrates? Justify your answer.

They are more closely related to us because they are deuterostomes like us Signup and view all the answers

Identify the four major characteristics of echinoderms.

Pentaradial symmetry, Ossicles, Water-vascular system, Tube feet Signup and view all the answers

What is the meaning of the name Crinoidea?

Lily-like Signup and view all the answers

What is the meaning of the name Ophiuroidea?

Snake-like Signup and view all the answers

What is the meaning of the name Echinoidea?

Spine-like Signup and view all the answers

What is the meaning of the name Holothuroidea?

Water polyp Signup and view all the answers

What is the meaning of the name Asteroidea?

Starlike Signup and view all the answers

Name examples of echinoderms in class Crinoidea.

Sea lilies & feather stars Signup and view all the answers

Name examples of echinoderms in class Ophiuroidea.

Basket stars & brittle stars Signup and view all the answers

Name examples of echinoderms in class Echinoidea.

Sea urchins & sand dollars Signup and view all the answers

Name an example of an echinoderm in class Holothuroidea.

Sea cucumbers Signup and view all the answers

Name an example of an echinoderm in class Asteroidea.

Sea stars (or starfish) Signup and view all the answers

Trace the flow of water through the Water-vascular system (WVS).

Water goes through the madreporite ➖ stone canal ➖ ring canal ➖ radial canal ➖ lateral canal ➖ ampullae ➖ tube feet Signup and view all the answers

What are general characteristics of class Asteroidea?

Typically have 5 arms which merge with a central disk (pentaradial symmetry). Mouth is located in the center of the oral surface which is directed downward. Signup and view all the answers

How do podia operate?

Ampulla contract and force fluid into the podia causing it to become extended. Suckers at the tips of the podia come into contact with the substrate and adhere to the surface. Then the podia contract, thereby forcing water back into the ampulla, and the body is pulled forward. Signup and view all the answers

Which one is bigger, the cardiac or the pyloric stomach?

Cardiac Signup and view all the answers

Explain the nutrition of organisms in class Asteroidea.

The mouth leads to a 2 part stomach: a cardiac stomach and a pyloric stomach. The pyloric stomach connects with digestive glands (pyloric cecae) that run into each arm. A short intestine extends from the pyloric stomach to an anus on the aboral surface. Associated with the intestine are rectal cecae that pump the fecal wastes out of the anus. Signup and view all the answers

What are additional characteristics of class Asteroidea?

The endoskeleton is made up of calcareous plates (ossicles) that often penetrate the dermis as spines. Between the spines and plates are projections called papulae, which function in gas exchange and excretion. Other projections in the body wall include jaw-like appendages called pedicellaria. Signup and view all the answers

What are general characteristics of class Echinoidea?

Lack arms. Body is enclosed in a test. Signup and view all the answers

Study Notes

General Echinodermata Characteristics

Examples include sea stars, sand dollars, sea urchins, and sea cucumbers.
Adult echinoderms exhibit radial symmetry, while larvae are bilaterally symmetrical.
Early echinoderms were sessile as adults, which led to the development of radial symmetry.
Approximately 80 species of echinoderms remain sessile today.
Unique characteristic: echinoderms are deuterostomes, linking them more closely to vertebrates than to other invertebrates.

Major Echinodermata Features

Four key characteristics:
- Pentaradial symmetry, where body parts extend from the center along five spokes.
- Ossicles, the calcium carbonate plates forming the endoskeleton, sometimes protruding through the skin.
- Water-vascular system, a network of water-filled canals aiding locomotion and feeding.
- Tube feet, small extensions for movement, feeding, respiration, and excretion.

Echinoderm Diversity

Total number of echinoderm species is around 7,000.
Five major classes of echinoderms:
- Crinoidea (e.g., sea lilies, feather stars) - meaning “lily-like”
- Ophiuroidea (e.g., basket stars, brittle stars) - meaning “snake-like”
- Echinoidea (e.g., sea urchins, sand dollars) - meaning “spine-like”
- Holothuroidea (e.g., sea cucumbers) - meaning “water polyp”
- Asteroidea (e.g., sea stars) - meaning “starlike”

Water-Vascular System (WVS)

Water circulates through the WVS via the following path: madreporite → stone canal → ring canal → radial canal → lateral canal → ampullae → tube feet.

Class Asteroidea Characteristics

Typically possess five arms merging with a central disk.
The mouth is located on the central oral surface facing downward.
Podia operate by fluid movement: the ampulla contracts, extending the podia. Suckers grip the substrate, the podia then retract, pulling the body forward.
Nutrition involves a two-part stomach system: cardiac (larger) and pyloric, leading to digestive glands in each arm.

Additional Class Asteroidea Features

Endoskeleton comprises calcareous plates (ossicles) and spines, with gas exchange facilitated by papulae.
Pedicellariae serve as jaw-like appendages for various functions.

General Class Echinoidea Characteristics

Members lack arms and exhibit a rounded body shape.

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Description

Test your knowledge about Phylum Echinodermata with these flashcards. You'll explore various echinoderm species, their symmetry, and historical movement patterns. Perfect for students studying marine biology or zoology.