Echinoderm

Indicate whether the sentence or statement is true or false.

Chordates and echinoderms have a common ancestor.

None of the echinoderms living in the oceans today is sessile.

In addition to radial symmetry, echinoderms have a water-vascular system.

The hard, spiny skin of an echinoderm is called an exoskeleton.

All echinoderms except the sand dollar display a five-part radial symmetry.

The adult form of all echinoderms exhibits radial symmetry.

Sea stars are carnivores and are among the most important predators in many marine ecosystems.

In some echinoderms, respiration and waste removal are performed by skin gills.

A separated piece of a sea star can regenerate the rest of its body as long as the piece contains part of the central region of the animal.

Identify the letter of the choice that best completes the statement or answers the question.

Embryological evidence suggests that the echinoderms are closely related to the

The first organisms to develop a hardened endoskeleton were the

Echinoderms

The symmetry exhibited by echinoderms is

In echinoderms and chordates, all the cells of the early embryo

The skeleton of an echinoderm is composed of individual plates called

sea cucumbers : a fused skeleton ::

Vertebrates, tunicates, and lancelets

Which embryonic chordate characteristics do lancelets retain as adults?

tunicates : in shallow- and deep-water environments ::

Some scientists have hypothesized that the first vertebrates, which were fish, may have evolved from an ancestral tunicate that became sexually mature in the larval form. They suggest that these reproducing larvae were successful and natural selection reinforced the absence of metamorphosis to the adult. Which of the following statements does not support the hypothesis that vertebrates evolved from a sexually mature larval tunicate?