Section 31.2 (Exam 3)

Question 1

What two groups do Ambulacrarians consist of?

Answer 1

Echinoderms and hemichordates

Question 2

What is a synapomorphy of amublacrarians (echinoderms and hemichordates)?

Answer 2

ciliated, bilaterally symmetrical larvae

Question 3

What type of symmetry to hemichordates have?

Answer 3

bilateral symmetry

Question 4

What type of symmetry do echinoderms have?

Answer 4

pentaradial symmetry

Question 5

What does pentaradial symmetry entail?

Answer 5

Echinoderm adults are pentaradially symmetrical. They have no head and move equally well in many directions.

Question 6

What are some important characteristics of echinoderms?

Answer 6

Pentaradial symmetry

Internal skeleton of fused calcified plates

A water vascular system

Takes in water through madreporites

Question 7

Describe an echinoderm internal skeleton.

Answer 7

fused calcified plates

Question 8

Describe the water vascular system of echinoderms and its functions.

Answer 8

Water vascular system: network of water-filled canals leading to extensions called tube feet.

Functions: gas exchange, locomotion, and feeding

Question 9

After water enters the echinoderm through the madreporites, where does it go?

Answer 9

Water then enters the ring canal around the esophagus. Radial canals radiate out from the ring canal.

Question 10

What are the three groups of echinoderms?

Answer 10

Crinoids

Echinozoans

Asterozoans

Question 11

What are the two types of crinoids?

Answer 11

Sea lilies and feather stars

Question 12

How do sea lilies attach to a substrate?

Answer 12

with a stalk

Question 13

How do feather stars attach to the substrate?

Answer 13

with flexible appendages that allow limited movement

Question 14

Describe some characteristics of sea lilies.

Answer 14

Attach to a substrate with a stalk.

Use tube feet on the arms for filter feeding.

Covered in mucus secreting glands.

Question 15

What are the two types of echinozoans?

Answer 15

Sea urchins and sea cucumbers

Question 16

Name some characteristics of sea urchins.

Answer 16

Lack arms

Have moveable spines

Question 17

What are some functions of sea urchin spines?

Answer 17

Locomotion, and some of them produce toxins

Question 18

How do sea urchins eat?

Answer 18

They catch plankton with their tube feet

Some scrape algae from rocks using a rasping structure similar to a radula

Question 19

Name three characteristics of sea cucumbers.

Answer 19

Lack arms

Front-to-back/mouth-to-anus body axis

Tube feet

Question 20

What are the tube feet in sea cucumbers used for?

Answer 20

Used for movement but more to anchor to substrate. Modified anterior tube feet (large feathery sticky) are used for feeding

Question 21

What is a common genus of sea cucumbers?

Answer 21

Pseudocolochirus

Question 22

What are two types of asterozoans?

Answer 22

sea stars and brittle stars

Question 23

What are some characteristics of sea stars?

Answer 23

Gonads and digestive organs in the arms

Tube feet have suction cups

Question 24

What is the function of tube feet in sea stars?

Answer 24

locomotion, gas exchange, attachment, capturing large prey

Question 25

What are some characteristics of brittle stars?

Answer 25

Flexible arms

Gonads and viscera are in the central disc

Tube feet lack suction cups

Question 26

What are two types of hemichordate?

Answer 26

Acorn worms and pterobranchs

Question 27

What are some characteristics of hemichordates?

Answer 27

Bilaterally symmetric

Three-part body

Question 28

What does the three-part body of hemichordates consist of?

Answer 28

proboscis, collar (containing mouth), and trunk (contains other body parts)

Question 29

What are some characteristics of acorn worms?

Answer 29

Up to 2 m long

Burrow (proboscis) in soft marine sediments

Question 30

What are some characteristics of pterobranchs?

Answer 30

Up to 12 mm long

Live in tubes secreted by the proboscis