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Intro Bio > Chapter 32- Animal Evolution > Flashcards

Chapter 32- Animal Evolution Flashcards

1
Q

cleavage

A
  • a succession of mitotic cell divisions w/o cell growth b/w the divisions
  • zygote undergoes cleavage to form the blastula
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2
Q

blastula

A
  • multicellular stage of the development of most animals that usually takes the form of a hollow ball
  • formed by cleavage of zygote
  • undergoes gastrulation to become gastrula
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3
Q

gastrulation

A
  • process during which the layers of embryonic tissues that will develop into adult body parts are produced
  • one end of the embryo folds inward, expands, and eventually fills the blastocoel, producing germ layers
  • preceded by the blastula stage
  • results in gastrula stage
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4
Q

gastrula

A
  • developmental stage resulting from gastrulation

- first stage to have germ layers

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5
Q

archenteron

A
  • pouch inside gastrula that is formed by gastrulation
  • opens to the outside via the blastopore
  • develops into “gut”
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6
Q

larva

A

sexually immature form of an animal that is morphologically distinct from the adult, usually eats a different food, and may even have a different habitat that the adult
-eventually undergo metamorphosis

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7
Q

metamorphosis

A

developmental transformation of an animal larva into a juvenile that resembles an adult but is not yet sexually mature

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8
Q

Hox genes

A
  • homeobox-containing family of genes unique to animals
  • play important roles in the development of animal embryos, controlling the expression of dozens or even hundreds of other genes that influence animal morphology
  • development of Hox genes proposed to be involved in the Cambrian explosion
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9
Q

Cambrian explosion

A
  • a wave of animal diversification that occurred 535-525 million years ago
  • great increase in the diversity of animal phyla
  • decline in the diversity of Ediacaran life forms
  • 3 popular hypotheses behind phenomenon: predator-prey relationships, atmospheric changes, and changes in the regulation of development
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10
Q

Ediacaran

A
  • first generally-accepted macroscopic fossils of animals appear
  • 565 to 550 million years ago
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11
Q

radial symmetry

A
  • type of symmetry found in a pie
  • has a dorsal/ventral orientation
  • lacks anterior/posterior and left/right orientation
  • commonly seen in sessile and planktonic animal
  • equips animal to meet the environment equally well from all sides
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12
Q

bilateral symmetry

A
  • two-sided symmetry seen in a shovel
  • has 2 axes of orientation: dorsal/ventral and anterior/posterior
  • typically found in actively moving animals
  • most bilateral animals have a CNS that enables them to coordinate complex movements
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13
Q

cephalization

A

an evolutionary trend commonly seen in animals w/ bilateral symmetry in which sensory equipment is concentrated at the anterior end, including a CNS in the head

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14
Q

ectoderm

A
  • germ layer covering the surface of the embryo

- gives rise to the outer covering of the animal and CNS

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15
Q

endoderm

A
  • innermost germ layer that lines the archenteron

- gives rise to the lining of the digestive cavity and organs such as the liver and lungs

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16
Q

diploblastic

A
  • describes an animal w/ only 2 germ layers (ectoderm and endoderm)
  • includes cnidarians and ctenophorians
17
Q

mesoderm

A
  • 3rd germ layer found in all bilaterally symmetrical animals
  • fills most of the space b/w the ectoderm and endoderm
  • forms the muscles and most other organs b/w the digestive tract and the outer covering of the animal
18
Q

triploblastic

A
  • describes an animal w/ all 3 germ layers

- includes all animals w/ bilateral symmetry

19
Q

coelom

A

-body cavity found in most triploblastic animals

20
Q

body cavity

A
  • a fluid- or air-filled space located b/w the digestive tract and the outer body wall
  • holds internal organs
21
Q

protostome development

A
  • mouth 1st
  • spiral and determinate cleavage
  • solid masses of mesoderm split and form coelom
  • blastopore becomes mouth
  • eg, molluscs, annelids
22
Q

deuterostome development

A
  • mouth 2nd (anus 1st)
  • radial and indeterminate cleavage
  • folds of archenteron form coelom (outpockets)
  • blastopore becomes anus
  • eg, echinoderms, chordates
23
Q

spiral cleavage

A
  • cleavage in which the planes of cell division are diagonal to the vertical axis of the embryo
  • smaller cells are centered over the grooves b/w larger underlying cells
24
Q

determinate cleavage

A
  • cleavage that rigidly casts the developmental fate of each embryonic cell very early
  • isolated cell cannot form into a whole animal
25
Q

radial cleavage

A
  • cleavage in which the planes of cell division are either parallel or perpendicular to the vertical axis of the embryo
  • tiers of cells are aligned, one directly above the other
26
Q

indeterminate cleavage

A
  • cleavage that produces cells with the capacity to develop into a complete embryo
  • how multiple offspring are possible (e.g., twins)
27
Q

blastopore

A
  • indentation that during gastrulation leads to the formation of the archenteron
  • opening of gastrula
28
Q

metazoa

A

-monophyletic clade including all animals

29
Q

eumetazoans

A
  • clade of “true animals” with true tissues

- includes all animals except sponges

30
Q

bilaterians

A
  • clade of animals w/ bilateral symmetry and 3 germ layers
  • contains the majority of animal phyla (all except porifera, cnidaria, and ctenophora)
  • Cambrian explosion was primarily a rapid diversification of bilaterians
31
Q

ecdysozoans

A
  • clade of animals in molecular phylogeny that secrete exoskeletons
  • dependent on a hormone
  • includes nematodes and arthropods
32
Q

lophotrochozoans

A
  • clade of animals in molecular phylogeny that may develop lophophores or go through a trochophore larval stage
  • dependent on feeding mode
  • includes platyhelminthes, rotifers, ectoprocts, brachiopods, molluscs, and annelids
33
Q

lophophore

A
  • a structure consisting of a crown of ciliated tentacles that function in feeding
  • found in some lophotrophozoans, such as ectoprocts
  • “crest”“carry”
34
Q

trochophore larva

A

-larval stage of development found in some lophotrophozoans

Intro Bio (6 decks)

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