An introduction to animal diversity Flashcards

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1
Q

Hox genes

A

They control early development in animal groups. Mutations in these genes could have resulted in rapid changes in animal body plans.

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2
Q

Early evolution of animals began in…

A

The cambrian radiation.

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3
Q

Ectoderm

A

The outer layer which gives rise to the body covering and the nervous system.

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4
Q

Endoderm

A

The inner layer, which lines the gut and other digestive organs.

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5
Q

Mesoderm

A

The middle layer, which gives rise to muscle, skeletal structures and most other body structures.

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6
Q

Acoelomate

A

Animals that have no cavity.

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7
Q

Coelomate

A

Animals that have a true coelom, a body cavity completely lined with mesoderm.

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8
Q

Pseudocoelomate

A

Animal that have a body cavity that is not completely lined with mesoderm.

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9
Q

Protostomes

A

Mollusks, annelids and arthropods. They undergo spiral cleavage, which is also determinate (the fate of each cell is fixed very early). The blastopore develops into the mouth.

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10
Q

Deutorostomes

A

Echinoderms and chordates. They undergo radial cleavage, which is indeterminate. The blastopore typically becomes the anus.

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11
Q

Hemichordates

A

They are marine deuterostomes with a three-part body, including proboscis, collar, and trunk.

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12
Q

Chordates

A

They include the tunicares, lancelets and vertebrates. At some time in its life cycle, a chordate has a flexible, supporting notochord, a dorsal tubular nerve cord, a muscular postanal tail and an endostyle or thyroid gland.

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13
Q

Vertebrates

A

They have a vertebral column composed of vertebrae. Neural crest cells are embryonic cells important in the development. They have complex brain, a muscular pharynx and muscles attached to the endoskeleton.

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14
Q

Tetrapods

A

They give rise to land vertebrates. They include the amphibian clades and the amniote lineage.

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15
Q

Amniotes

A

Terrestrial vertebrates. Adaptations for life on land include: 1, the evolution of the amniotic egg with its shell and amnion, 2, internal fertilization and 3, a body covering that retards water loss and physiological mechanisms that conserve water.

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16
Q

Mammals

A

Several derived characters like mammary glands, hair, one pair of temporal openings in the skull, differentiated teeth, lungs with alveoli, ventricles, three middle-ear bones, neocortex.

17
Q

Protherians

A

Monotremes or mammals that lay eggs.

18
Q

Therians

A

They bear their young alive. This clade includes metatheria and eutheria.