general zoology - quiz no.2

What do echinoderm fossils and larvae indicate?

That they are bilaterally symmetrical and pentaradial symmetry is dervied

What type of symmerty can be limiting for free-moving animals?

Radial symmetry

Where are echinoderms abundant?

In marine habitats

Why are echinoderms unique?

They possess features not seen in other phyla

How did hemichordates develop to differ from echinoderms?

They developed buccal diverticulum and mesocoelomic ducts

What superphylum do echinoderms and hemichordates belong to?

Deuterostomes

What trait were present in stem echinoderms but lost in modern echinoderms?

Gill slits

Are echinoderms vertebrates or invertebrates?

Invertebrates

Are hemichordates vertebrates or invertebrates?

Invertebrates

What does the clade ambulacraria contain?

Echinoderms and hemichordates

What are examples of echinoderms?

Sea stars and brittle stars

What are examples of hemichordates?

Acorn worms and pterobranchs

What do members of the clade ambulacraria share?

Deuterstome features, three-part coelom, similar larval forms, and axial (specialized filtering) complex

What combination of characteristics are found in echinoderms but no other phylum?

A calcareous endoskeleton, large plates/small ossicles, a water-vascular system, pedicellariae, dermal brachiae, and pentaradial symmetry in adults

What type of symmetry do adult echinoderms have?

Pentaradial symmetry

Were most early forms of echinoderms free-moving or sessile?

Sessile with radial symmetry

What class of echinoderms still has sessile forms?

Crinodiea

Are most modern echinoderms sessile or free moving?

Free-moving

What are ancestral deuterostomes envisioned as?

Benthic filter-feeder ingesting particles via ciliary water movement

What are the two forms of echinodermata?

Yanjiahella and ctenoimbricata

What are characteristics of the Yanjiahella form of echinoderms?

It is a bilateral, two-armed form

What are characteristics of the Ctenoimbricata form of echinoderms?

It is a benthic, bilateral forn with a ventral mouth

While all echinoderms are marine organisms, they have a limited ability to do what?

Osmoregulate

Where are most adult echinoderms?

At low points of the sea (benthic)

While some echinoderms are particle feeders, many are what?

Predators

What phylum do regular and irregular sea urchins belong to?

Echinoderms

What do regular sea urchins feed on?

Algae

What do irregular sea urchins feed on?

They are deposit feeders

What phylum do crinoids belong to?

Echinoderms

What do crinoids feed on?

Plankton and suspended particles

What echinoderms are the most active?

Brittle stars

How do brittle stars feed?

Thy are scavengers, browsers, and deposit or filter feeders

What do some brittle stars have a commensalism relationship with?

Sponges

What type of axis do sea cucumbers have?

An extended oral-aboral axis

What is the sea cucumbers primary feeding method?

Suspension or deposit feeding

What class of echinoderms are sea stars?

Asteroidea

Where are sea stars commonly found?

Along shorelines, rocks, muddy/sandy bottoms, or coral reefs

Approximately how many living species of sea stars are there?

1500

What size are sea stars?

Range from a cm to a meter across

What color are sea stars?

Often bright colored

What are the external features of asteroids (sea stars)?

A central disc with 5+ tapering and extending arms

What is the oral surface of an asteriod (sea stars)?

The surface with the mouth

What is on the aboral surface of an asteriod (sea stars)?

The surface opposite of the mouth

What is the ambulacrum of an asteroid (sea star)?

Region from the mouth to the tip of each arm

What borders the ambulacral groove of an asteroid (sea star)?

Rows of tube feet

What borders the rows of tube feet of an asteroid (sea star)?

Moveable spines

What are at the end of arm of an asteroid (sea star)?

Sensory tentacles

What is the circular madreporite of an asteroid (sea star)?

A porous plate that allows water to enter the water-vascular system

Where is the circular madreporite of an asteroid (sea star) located?

On the aboral surface

Where is the radial nerve of an asteroid (sea star) located?

In the center of the ambulacral grooves

What is under the radial nerve of an asteroid (sea star)?

The extension of the coelom

What is the extension of the coelom of an asteroid (sea star)?

The radial canal of the water-vascular system

Ossicles/dermal tissues that cover the structure of asteroids (sea stars) are present in all classes expect what?

Crinoids

What is the usual texture of the aboral surface of an asteroid (sea star)?

Rough and spiny

What do many asteroid (sea star) species have that keep the body free of debris?

Pincer-like pedicellariae

What are papulae (dermal branchiae or skin gills) of an asteroid (sea star)?

Soft projections between ossicles for gas exchange

What penetrates between the ossicles of an asteroid (sea star)?

Tube feet (podia)

What type of pedicellaria of an asteroid (sea star) are associated with muscles?

Forceps-type pedicellaria

What is under the epidermis of an asteroid (sea star)?

The mesodermal endoskeleton

What is the mesodermal endoskeleton of an asteroid (sea star) made of?

Small calcareous plate (ossicles)

What binds the mesodermal endoskeletonWossicles of an asteroid (sea star) together?

Connective tissue called catch collagen

What is the stereom of an asteroid (sea star)?

The porous, mesh-like structure of the ossicles with spaces filled with fibers and dermal cells

What gives rise to several adult structures of adult asteroid (sea star) structures?

Larval coelomic compartments

What is the coelom of an asteroid (sea star)?

A spacious fluid-filled body cavity

What circulates fluid through the coelom to the papulae of an asteroid (sea star)?

The ciliated peritoneal lining

How do asteroids (sea stars) remove gases and waste?

Throgh diffusion across the papulae and tube feet

What gas do asteroids (sea stars) primarily diffuse?

Ammonia

What organs do asteroids (sea stars) replace with diffusion?

Kidneys and lungs

What system is a coelomic compartment that is unique to echinoderms?

The water-vascular system

What does the water-vascular system of an asteroid (sea star) consist of?

A system of canals and tube feet with dermal ossicles the form a hydraulic system

What are the functions of water-vascular system of an asteroid (sea star)?

Locomotion, food-gathering, respirattion, and excretion

What does the madreporite of an asteroid (sea star) lead to?

The stone canal → the ring canal that encircles the mouth

What extends from the ring canal of an asteroid (sea star)?

Radial canals that extend into each ray

What functions as fluid reservoirs in the water-vascular system of an asteroid (sea star)?

Polian vesicles that can attach to the ring canal

What connects the radial canal to the tube feet (podia) of an asteroid (sea star)?

Small lateral canals, each with a one-way valve

What does the inner end of a tube foot of an asteroid (sea star) consist of?

An ampulla that lies within the coelom

What does the outer end of a tube foot of an asteroid (sea star) consist of?

A sucker

What do the ampulla muscles of the water-vascular system of asteroids (sea stars) do?

Contract and force extension and fluid into podium

What forces fluid back into the ampulla from the podium of an asteroid (sea star)?

Contraction and retraction of the tube foots longitudinal muscle

What creates suction for locomotion of an asteroid (sea star)?

When the small muscles in the end of the tube foot raise in the middle section

How much pull can the suction of tube foot of an asteroid (sea star) create?

0.25 - 0.30 newtons

What allows an asteroid (sea star) to move vertical surfaces?

Coordinated action of all or many tube feet

How is the locomotion of an asteroid (sea star) different on soft surfaces?

Suckers are ineffective, causing tube feet to operate like legs

What does the mouth of an asteroid (sea star) lead to?

A two-part stomach in the central disc

What are the two parts of the stomach of an asteroid (sea star)?

The larger lower cardiac stomach and the smaller upper pyloric stomach

Which stomach of an asteroid (sea star) can be everted through the mouth during feeding?

The large lower cardiac stomach

What is the upper pyloric stomach of an asteroid (sea star) connected to?

Pyloric ceca (digestive glands) in each arms

Where does digestion occur in an asteroid (sea star)?

Mostly extracellularly in the pyloric ceca

Do all asteroids (sea stars) have an intestine and anus?

No, some species lack both

What do asteroids (sea stars) feed on?

Invertebrates, vertebrates, and particles

What species of asteroids (sea stars) prey on mussels and oysters?

Asterias

What species of asteroids (sea stars) is damaging the coral reef in the Pacific Ocean?

Crown-of-thorns starfish

How are crown-of-thorns starfish damaging the coral reef?

They feed on coral polyps

How do the diets of crown-of-thorns starfish change based on their population size?

Low population, they eat the faster-growing corals. High population, they eat all corals

What causes the population of crown-of-thorn to increase?

Nutrient run off increases plankton population. Plankton are food for larval sea stars

What is the hemal system of an asteroid (sea star)?

A system of tissue stands enclosing perihemal channels

What does the hemal system of an asteroid (sea star) play a role in?

Distributing nutrients

Is the hemal system of an asteroid (sea star) developed fully?

No, it is not developed well

What do echinoderms lack in their nervous system?

A brain and distinct ganglia

How many subsystems does the nervous system of echinoderms have?

Three systems that each have a ring and radial nerves, and occur at different levels in the disc and arms