Invertebrate Zoology Chapter 2

Front 1

Metazoans

Back 1

True animals are multicellular, generally diploid organisms that each develop form a blastula

Front 2

Cambrian Explosion

Back 2

The amazingly sudden appearance and apparently rapid diversification of complex animals over several millions of years

Front 3

Unicellular

Back 3

Single celled

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Acellular

Back 4

Without cell

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Bilaterally symmetrical

Back 5

Possessing right and left sides that are approximate mirror images of each other.

Front 6

Cephalization

Back 6

The concentration of nervous and sensory tissues and organs at one end of the an animal, resulting in a distinct anterior and posterior ends.

Front 7

Radially symmetrical

Back 7

An animal that can be divided into two approximately equal halves by any cut that passes through its center.

Front 8

Germ Layers

Back 8

Are groups of cells that behave as a unit during the early stages of embryonic development and give rise to distinctly different tissue and/or organ systems in the adult.

Front 9

Diploblastic

Back 9

Only have two distinct germ layers form during or following the movement of cells into the embryo's interior.

-Ectoderm

-Endoderm

Front 10

Ectoderm

Back 10

The outer most layer of cells.

Front 11

Endoderm

Back 11

The inner most layer of cells.

Front 12

Triploblastic

Back 12

During the ontogeny cells of the ectoderm or most often the endoderm give rise to a third germ layer the mesoderm. Having three distinct germ layer during early embryonic development.

Front 13

Mesoderm

Back 13

Always lies b/t the outer ectodermal tissue and the inner endodermal tissue.

Front 14

Acoelomate

Back 14

Triploblastic animals lacking an internal body cavity.

Front 15

Blastocoel

Back 15

An internal space that develops in the embryo prior to gastrulation

Front 16

Pseudocoel

Back 16

The coelom that is lined with the mesoderm and the endoderm.

Front 17

pseudocoelomate

Back 17

The animal having a pseudocoel

Front 18

Coelom

Back 18

An internal, fluid-filled body cavity lying b/t the gut and the outer body wall musculature and lined with tissue derived form embryonic mesoderm.

Front 19

Coelomates (Eucoelomates)

Back 19

The animals possessing a coelom

Front 20

Protostomes

Back 20

The Triploblast formation of the coelom occurs via Schizocoely

Front 21

Schizocoely

Back 21

The coelom formation occurs by gradual enlargement of a split in the mesoderm

Front 22

Enterocoely

Back 22

The coelom formation occurs by the evagination of the archenteron in the embryonic blastocoel

Front 23

Deuterostomes

Back 23

The Triploblast formation of the coelom occurs via Enterocoely

Front 24

Animal Pole

Back 24

The nucleus occurs in or moves to, the region of lower yolk density

Front 25

Vegetal Pole

Back 25

The opposite end of the egg when compared to the animal pole.

Front 26

Radial Cleavage

Back 26

Cleavage occurs either parallel or perpendicular to the animal-vegetal axis.

Front 27

Spinal Cleavage

Back 27

Cleavage occurs at 45 degree angles to the animal-vegetal axis.

Front 28

Micromeres

Back 28

A group of smaller cells that are often seen lying with the macromeres during the eight cell stage.

Front 29

Macromeres

Back 29

A the larger cells present during the eight cell stage.

Front 30

Polar Lobe

Back 30

Is a conspicuous bulge of cytoplasm that forms prior to cell division is complete, the bulge is resorded into the daughter cell to which it is still attached.

Front 31

Taxon

Back 31

Any named group of organisms that is sufficiently distinct to be assigned to such a category

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Monophyletic

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Groups must also include all descendants of the originating ancestor.

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Paraphyletic

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Groups that does not include all descendants of the originating ancestor.

Front 34

Species

Back 34

Reproductively isolated. Members that form a pool of genetic trait.

Front 35

The PhyloCode

Back 35

The proposed replacement for the Linnaean system (the current classification system). Is hierarchical-is rankless.

Front 36

Convergence

Back 36

Distantly related animals may come to resemble each other rather closely, but come about via different evolutionary paths.

Front 37

Analogous

Back 37

Features that resemble each other through convergence

Front 38

Homology

Back 38

Features the resemble each other through the same evolutionary path

Front 39

Synapomorphies

Back 39

The only characters of importanctance in establishing evolutionary relationship. Shared characters derived from a common ancestor in which the characters originated. split into two groups.

Front 40

Parsimonious

Back 40

Way of explaining the evolutionary history of these groups.

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Sister groups

Back 41

The two closest related groups on a cladogram

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intertidal

Back 42

Living b/t the physical limits of high and low tides and thus exposed to air periodically

Front 43

Subtidal

Back 43

living below the low-tide line and thus exposed to air only under extreme conditions, if ever

Front 44

Sessile

Back 44

inmobile

Front 45

Planktonic

Back 45

Forced to drift or wander

Front 46

Herbivores

Back 46

Plant eater

Front 47

Carnivores

Back 47

Flesh eaters

Front 48

Suspension feeders

Back 48

Remove small food particles from the surrounding medium

Front 49

Deposit feeders

Back 49

ingest sediment, digesting the organic component as the sediment moves through the digestive tract

Front 50

symbiotic Associations (symbioses)

Back 50

Member of one sp. frequently live in intimate association w/ those of another sp.

Front 51

Symbionts

Back 51

The participants of a symbiotic association or symbioses

Front 52

Ectosymbionts

Back 52

live near or on the body of the other participant

Front 53

Endosymbionts

Back 53

live w/i the body of the other participants

Front 54

Mutualism

Back 54

When both symbionts benefit

Front 55

Commensalism

Back 55

When one symbiont is benefited and the other is neither harm or benefited

Front 56

Parasites

Back 56

They depend upon their host for continuation of the sp.

Front 57

Phenetics

Back 57

Based entirely on degree of overall anatomical and biochemical similarity, w/o regard to whether the similarities reflect homology or convergence

Front 58

Cladistic (Phylogenetic) Classification

Back 58

Based entirely upon recency of common descent inferred form the mutual possession of particular specialized derived morphological traits

Front 59

Evolutionary Classification

Back 59

Attempts to consider both ancestry and the degree to which an organisms have subsequently diverged from the ancestral form.