Chapter 32: An Introduction to Animal Diversity

Question 1

Cleavage

Answer 1

A succession of mitotic cell divisions without cell growth between division cycles. This leads to a blastula.

Question 2

Blastula

Answer 2

A multicellular stage which in many animals takes the form of a hollow ball. This leads to gastrulation.

Question 3

Gastrulation

Answer 3

A process during which layers of embryonic tissues that will develop into adult body parts are produced. This results in a gastrula.

Question 4

Gastrula

Answer 4

An embryonic stage succeeding gastrulation, which consists of an “indent” of endoderm cells and a shell of ectoderm cells.

Question 5

Archenteron

Answer 5

The developing digestive tube, which gives rise to its lining and related organs such as liver and lungs. The blind pouch formed by gastrulation, which opens to the outside via the blastopore.

Question 6

Blastopore

Answer 6

Opening from the archenteron to the outside of a gastrula.

Question 7

Blastocoel

Answer 7

Inside of the blastula and gastrula stages of animal development.

Question 8

Closest Living Relatives of Animals

Answer 8

Choanoflagellates

Question 9

Ediacaran Fauna

Answer 9

The first generally accepted fossils of animals. 575 mya. Appear similar to corals, mollusks, and worms

Question 10

Cambrian Explosion

Answer 10

The period between 542 and 525 mya when most of the earliest ancestors of extant animal phyla appeared.

Question 11

Neoproterozoic Era

Answer 11

1 Billion–542 Million. First Animal Fossils.

Question 12

Paleozoic Era

Answer 12

542 Million–251 Million. Cambrian Explosion. Vertebrate and Arthropod Transition to Land.

Question 13

Mesozoic Era

Answer 13

251 Million–65 Million. Adaptive Radiation. Filling Niches. Dinosaurs. First Mammals.

Question 14

Cenozoic Era

Answer 14

65.5 Million–Present. Mammals take over for extinct dinosaurs. Global cooling. Apes adapted to new grasslands and became humans.

Question 15

Grade

Answer 15

A group of animal species that share the same level or organizational complexity.

Question 16

Body Plan

Answer 16

The set of morphological and developmental traits that define a grade are integrated into a body plan.

Question 17

Radial Symmetry

Answer 17

Identical planes can be spun around an axis. Sea Anemones.

Question 18

Bilateral Symmetry

Answer 18

Plane from which identical halves emanate. Lobster.

Question 19

Dorsal Side

Answer 19

Top Side

Question 20

Ventral Side

Answer 20

Bottom Side

Question 21

Anterior End

Answer 21

Head End

Question 22

Posterior End

Answer 22

Tail End

Question 23

Cephalization

Answer 23

The concentration of sensor equipment at the anterior end of bilaterally symmetric animals.

Question 24

Tissues

Answer 24

Collections of specialized cells isolated from other tissues by membranous layers.

Question 25

Ectoderm

Answer 25

The germ layer covering the surface of the embryo, gives rise to the outer covering of the animal and its nervous system.

Question 26

Endoderm

Answer 26

The innermost germ layer, lines the developing digestive tube, or archenteron

Question 27

Diploblastic

Answer 27

Animals with only ectoderm and endoderm. Cnidarians.

Question 28

Mesoderm

Answer 28

The germ layer between endoderm and ectoderm which forms muscle and organs between other layers.

Question 29

Triploblastic

Answer 29

Having three germ layers.

Question 30

Germ layers

Answer 30

Concentric layers of tissues formed through gastrulation.

Question 31

Body Cavity

Answer 31

A fluid-filled space separating the digestive tract from the outer body wall. A true body cavity is formed from the mesoderm.

Question 32

Coelum

Answer 32

Body Cavity

Question 33

Coelumates

Answer 33

Animals with a true coelum.

Question 34

Pseudocoelumates

Answer 34

Animals with a coelum derived from the blastocoel rather than the mesoderm.

Question 35

Acoelumates

Answer 35

Animals with no coelum.

Question 36

Protostome Development

Answer 36

Development characterized by spiral cleavage (often with determinate cleavage), schizocoelous development of the coelum, and a blastopore which becomes the mouth.

Question 37

Deuterostome Development

Answer 37

Development characterized by radial cleavage (usually with indeterminate cleavage), enterocoelous development of the coelum, and a blastopore which becomes the anus.

Question 38

Spiral Cleavage

Answer 38

Development with planes of cell division diagonal to the vertical axis of the embryo. Protostome.

Question 39

Determinate Cleavage

Answer 39

Cleavage associated with spiral cleavage and protostomes, in which the fate of cells is determined very early by differentiation.

Question 40

Radial Cleavage

Answer 40

Development of radial planes of cell division parallel or perpendicular to the vertical axis of the egg. Deuterostome.

Question 41

Indeterminate Cleavage

Answer 41

Cleavage associated with radial cleavage and deuterostomes, in which the fate of cells is not determined early on and the cells can each form full organisms for a time.

Question 42

Schizocoelous Development

Answer 42

Development of the Coelum (body cavity) from masses of mesoderm that have split off of the archenteron.

Question 43

Enterocoelous Development

Answer 43

Development of the Coelum (body cavity) from mesoderm buds on the wall of the archenteron.

Question 44

Animal Ancestry

Answer 44

All animals share a common ancestor.

Question 45

Parazoan

Answer 45

Beside the animals. Sponges are basal animals.

Question 46

Eumetazoa

Answer 46

A clade of animals with true tissues.

Question 47

Bilateria

Answer 47

Defines large clade and grade called bilaterians.

Question 48

Deuterostomia

Answer 48

Clade that includes vertebrates.

Question 49

Ecdysozoans

Answer 49

Taxa defined using molecular systematics that is a sister to lophotrochozoans and deuterostomia in the bilateria clade. It refers to the secretion of exoskeletons from which animals molt.

Question 50

Lophotrochozoans

Answer 50

Taxa defined using molecular systematics that is a sister to deuterostomia and ecdysozoans in the bilateria clade. It is defined by either a lophophore or a stage called a trochophore larva.

Question 51

Lophophore

Answer 51

A ciliated crest that helps in feeding.

Question 52

Trochophore larva

Answer 52

A distinctive larval stage.