BIOL113 L30

what are endoskeletons?

Endoskeletons are internal support structures found within the bodies of some animals. Unlike exoskeletons, which are external shells or coverings, endoskeletons lie within the body, providing support, protection, and points of attachment for muscles.

Which invertebrate groups have endoskeletons?

Echinoderms and Sponges.

What are the functions of a skeleton?

Support, protection, and movement.

What are the deuterostome characteristics shared by echinoderms and phylum Chordata?

Radial cleavage, development of the coelom from the archenteron, and the formation of the anus from the blastopore

What is the unique feature of echinoderms' endoskeleton?;

A thin skin covers an endoskeleton of hard calcareous plates

What is the function of the water vascular system in echinoderms?

It functions in locomotion, feeding, and respiration.

How do echinoderms reproduce?

Sexual reproduction involving the release of gametes by males and females into the seawater.

How do echinoderm adults develop?

Radial adults develop by metamorphosis from bilateral larvae.

How many classes are echinoderms divided into?

Six classes.

What are the names of the classes into which echinoderms are divided?;

Asteroidea, Ophiuroidea, Echinoidea, Crinoidea, Holothuroidea, and Concentricycloidea.

What are the characteristics of sea stars (class Asteroidea)?

They have arms radiating from a central disk, undersides of the arms have rows of tube feet, and they use the tube feet to grasp the substrate, move, or capture prey.

How does a sea star feed on closed bivalves?

It everts its stomach through its mouth and into the narrow opening between the shells of the bivalve.

What do enzymes from the sea star's digestive organs do when feeding on closed bivalves?

They begin to digest the soft body of the bivalve inside its own shell.

What can sea stars and some other echinoderms do when they lose an arm?

Regrow an entire body from a single arm.

What are the characteristics of brittle stars (class Ophiuroidea)?

They have a distinct central disk, long, flexible arms, and move by serpentine lashing of their arms.

What do the tube feet of brittle stars lack?

suckers

How do sea urchins and sand dollars move?

Sea urchins can move by pivoting their long spines, while sand dollars use their five rows of tube feet for locomotion.

What are the mouth structures of sea urchins adapted for?

The mouth of an urchin is ringed by complex jawlike structures adapted for eating seaweed and other foods. 

What are the characteristics of the class Crinoidea?;

It includes sea lilies attached to the substratum by stalks and feather stars that crawl using their long, flexible arms, and both use their arms for suspension-feeding.

What is the appearance of sea cucumbers (class Holothuroidea) compared to other echinoderms?

They lack spines, have a much reduced hard endoskeleton, and an elongated oral-aboral axis.

What function do some tube feet around the mouth of sea cucumbers serve?

They function as suspension-feeding or deposit feeding tentacles.

How many invertebrate subphyla are included in the phylum Chordata?

two

To which phylum do humans belong?

chordata

How long have echinoderms and chordates existed as distinct phyla?

for at least half a billion years.

what are the two groups of deuterostomes?

echinoderms and chordates

What similarities do echinoderms and chordates share despite being distinct phyla?

they share similarities in early embryonic development.

What are the characteristics of the hydrostatic skeleton?

It consists of fluid held under pressure in a closed body compartment, and its form and movement are controlled by changing the shape of this compartment.

What are exoskeletons composed of in arthropods?

A cuticle, with about 30-50% consisting of chitin, and muscles are attached to the interior surface of the cuticle.

What are the hard supporting elements within soft tissues in endoskeletons?

Sponges have spicules, echinoderms have plates composed of magnesium carbonate and calcium carbonate, and chordate endoskeletons are composed of cartilage and bone.

How are the bones of the mammalian skeleton connected at joints?

by ligaments