Biology test 1: Subject 1, Animal phylogeny

monophyletic

derived from a single common ancestor

polyphyletic

derived from more than one common ancestor

Nervous Tissue

present in animals. neurons and supporting cells function to conduct signals.

muscle tissue

functions in movement via contraction. contraction results from the interaction of actin & myosin

3 muscle tissues

smooth, cardiac, skeleton.

neuron

cells that transmit signals to and from muscles.

metazoa

multicellular animals

Parazoa

group within metazoan that lack true tissues

Eumetazoa

true tissues are present

Radiata

animals with radial symmetry

radial symmetry

more than 2 planes passing through the longitudinal axis divide the body into similar halves. body has one main axis around which the body parts are arranged.

radiata animal examples

Ctenophora, cnidaria

Bilateral symmetry

animal can be divided into mirror-image right and left sides by a mid-saggital plane (plane going through middle)

Anterior

The front or head end of an orgasm or body part.

Posterior

The back or tail end of an organism or body part.

Dorsal

The upper or back side of an organism or body part.

Ventral

The lower or belly side of an organism or body part

Lateral

The sides of an organism, away from midline

Medial

towards the midline or center of an organisms body.

germ layers

tissues that come from embryonic layers.

Endoderm

The innermost germ layer of an embryo. Develops into the digestive system, liver, pancreas, and respiratory system.

Ectoderm

The outtermost germ layer of an embryo, gives rise to the skin, nervous system, and sensory organs.

Mesoderm

the middle germ layer of embryo which develops into muscles, bones, the circulatory system, and other internal structures

diploblastic

animals that develop from embryos with 2 germ layers.

triploblastic

animals that develop from embryos with 3 germ layers.

Germ layers in a triploblastic animal

ectoderm is outer covering and nervous system, endoderm is gut liver and lungs, mesoderm is muscles.

diploblastic animals

cndiarians and ctenophores develoop from 2 germ layers

triploblastic animals

platyhelminths, echinoderms, chordates, mollusks, arthropods, annelids

cephalization

evolutionary trend towards concentrating nervous and sensory structures at the anterior end.

acoelomate

no body cavity, region between gut and body wall is filled with tissues. ex phylum platyelminthes

Pseudocoelomate (= blastocoelomate)

body cavity present but not enclosed on all sides by tissue derived from mesoderm. ex phylum nematoda

Coelomate

body cavity is present and is enclosed on all sides by tissue derived from mesoderm. ex phylum annelida

Protosome

development characteristic where the blastophere becomes mouth and cleavage is spiral.

Deuterostome

development characteristic where blastophere becomes anus and cleavage is radial.

lophotrochozoan

protostome group. possesses a lophophore and/or a torchopore larva. includes ectropocts, molluscs , and annelids.

Ecdysozoa

protosome group. Needs to shed their exoskeleton to grow this is known as molting or ecdysis. includes arthropods and nematodes (round worms).

zygote

fertilized egg

cleavages

numerous cell divisions that the zygote undergoes.

blastula

stage at which the embryo is a hollow ball of cels.

gastrulation

formation of a layered embryo (gastrula). may occur in invagination

blastocoel

The fluid-filled cavity inside a blastula that provides space for cell movement during early embryonic development.

blastopore

The opening that forms during gastrulation, which can develop into the mouth in protostomes or the anus in deuterostomes.

archenteron

The primitive gut formed during gastrulation that eventually develops into the digestive tract of the organism.