Chapter 32: The Deuterostomes

Frog embryos

Frog embryos

________ develop into tadpoles, which undergo metamorphosis to become adults.

hagfishes

The ________, which make up the Myxini, and the lampreys, which make up.

Biologists

________ classify amniotes in two main groups: diapsids and synapsids.

Jaws

________ and paired fins are absent in both hagfishes and lampreys.

Tiktaalik

________ was a transitional form between fishes and tetrapods.

Hemichordates

________ (acorn worms) are marine deuterostomes with a three- part body, including proboscis, collar, and trunk.

Echinoids

________ lack arms; they have a solid shell and are covered with spines.

Mammals

________ have hair, mammary glands, differentiated teeth, lungs with alveoli, completely divided ventricles, and three middle- ear bones.

Eutherians

________ are more developed at birth than marsupials; they are characterized by a well- developed placenta, an organ of exchange that develops between the embryo and the mother.

Synapsids

The ________ include the therapsids, which gave rise to the mammals.

Class Holothuroidea

________ consists of sea cucumbers, animals with elongated flexible bodies.

Amphibians

________ use their moist skin as well as lungs for gas exchange.

Class Asteroidea

________ consists of the sea stars.

Birds

________ have many adaptations for powered flight, including feathers; wings; and light, hollow bones containing air spaces.

Vertebrates

________ have pronounced cephalization, a complex brain, a muscular pharynx, and muscles attached to the endoskeleton.

Class Ophiuroidea

________ includes the brittle stars, which resemble sea stars but have longer, more slender arms that are set off more distinctly from the central disc.

Lancelets

The ________ are cephalochordates, small, segmented, fishlike animals; their chordate characteristics are highly developed.

Petromyzontida

The ________, have neither jaws nor paired fins.

Monotremes

________ lay eggs.

oral surface of crinoids

The ________ is turned upward; some crinoids are sessile.

Neural crest cells

________ are embryonic cells important in the development of many structures, including the cranium and jaws.

central disc

They have a(n) ________ with five or more arms, and they use tube feet for locomotion.

Chondrichthyes

The ________ comprise the sharks, rays, and skates; they are jawed fishes with skeletons of cartilage.

Hagfishes

________ are marine scavengers that secrete slime as a defense mechanism.

jaws

They have ________, two pairs of fins, and placoid scales.

Vertebrates

________ can be assigned to nine classes.

Shared derived characters include

radial, indeterminate cleavage; the blastopore becomes (or is near the future site of) the anus; and pharyngeal slits at some time in the life cycle

The chordates (Phylum Chordata) include three subphyla

Urochordata, Cephalochordata, and Vertebrata

The extant (living) bony fishes can be assigned to three classes

Actinopterygii, ray finned fishes; Actinistia, coelacanths; and Dipnoi, lungfishes

During the Devonian period, bony fishes gave rise to two evolutionary lines

th Actinopterygii, or ray-finned fishes, and the Sarcopterygii, or lobe-finned fishes

Biologists classify amniotes in two main groups

diapsids and synapsids