Section 31.2 (Exam 3) Flashcards
Echinoderms and Hemichordates Are Restricted to Marine Environments (30 cards)
What two groups do Ambulacrarians consist of?
Echinoderms and hemichordates
What is a synapomorphy of amublacrarians (echinoderms and hemichordates)?
ciliated, bilaterally symmetrical larvae
What type of symmetry to hemichordates have?
bilateral symmetry
What type of symmetry do echinoderms have?
pentaradial symmetry
What does pentaradial symmetry entail?
Echinoderm adults are pentaradially symmetrical. They have no head and move equally well in many directions.
What are some important characteristics of echinoderms?
Pentaradial symmetry
Internal skeleton of fused calcified plates
A water vascular system
Takes in water through madreporites
Describe an echinoderm internal skeleton.
fused calcified plates
Describe the water vascular system of echinoderms and its functions.
Water vascular system: network of water-filled canals leading to extensions called tube feet.
Functions: gas exchange, locomotion, and feeding
After water enters the echinoderm through the madreporites, where does it go?
Water then enters the ring canal around the esophagus. Radial canals radiate out from the ring canal.
What are the three groups of echinoderms?
Crinoids
Echinozoans
Asterozoans
What are the two types of crinoids?
Sea lilies and feather stars
How do sea lilies attach to a substrate?
with a stalk
How do feather stars attach to the substrate?
with flexible appendages that allow limited movement
Describe some characteristics of sea lilies.
Attach to a substrate with a stalk.
Use tube feet on the arms for filter feeding.
Covered in mucus secreting glands.
What are the two types of echinozoans?
Sea urchins and sea cucumbers
Name some characteristics of sea urchins.
Lack arms
Have moveable spines
What are some functions of sea urchin spines?
Locomotion, and some of them produce toxins
How do sea urchins eat?
They catch plankton with their tube feet
Some scrape algae from rocks using a rasping structure similar to a radula
Name three characteristics of sea cucumbers.
Lack arms
Front-to-back/mouth-to-anus body axis
Tube feet
What are the tube feet in sea cucumbers used for?
Used for movement but more to anchor to substrate. Modified anterior tube feet (large feathery sticky) are used for feeding
What is a common genus of sea cucumbers?
Pseudocolochirus
What are two types of asterozoans?
sea stars and brittle stars
What are some characteristics of sea stars?
Gonads and digestive organs in the arms
Tube feet have suction cups
What is the function of tube feet in sea stars?
locomotion, gas exchange, attachment, capturing large prey
