chapter 27 - animal diversity

are multicellular eukaryotes, heterotrophy, active movement, reproduction, embryonic development, and a body plan

what are the 6 main features of the kingdom animalia?

sexual reproduction

the most common type of reproduction for animals

- usually separate sexes

- some are hermaphroditic

hermaphrodites

organisms that contain both female and male sex organs, requiring only one organism for sexual reproduction to take place

asexually reproduction

the type of reproduction that occurs through fragmentation, regeneration, budding, or parthenogenesis in animals

parthenogensis

type of asexual reproduction in which a new individual develops from an unfertilized egg

life cycle patterns

diploid zygote undergoes mitosis -> multicellular diploid adult that then undergoes meiosis -> haploid gametes that undergo fertilization -> diploid zygote (and the cycle continues)

metamorphosis

change of form; usually occurs to allow larva to transform into an adult

gradual change

process that occurs when animal DOESN'T have a larval stage, instead they slowly go from a juvenile stage to an adult stage

gastrulation

the process in which a gastrula develops from a blastula by the inward migration (folding) of cells -> creation of germ layers

blastopore

the opening of the central cavity of an embryo in the early stage of development

archentron

cavity inside of gastrula that serves as the precursor to the digestive tract

the endoderm and ectoderm form first, then the mesoderm later forms between them

what order do germ layers form in?

ectoderm

the outermost germ layer that develops into skin and nervous tissue

endoderm

the innermost germ layer; develops into the linings of the digestive tract, internal organs, and the lungs

mesoderm

middle germ layer; develops into muscles, bone, blood and much of the circulatory, reproductive, and excretory systems

diploblastic animals

animals with two germ layers: ectoderm and endoderm

triploblastic animals

animals with three germ layers: ectoderm, endoderm, and mesoderm

protosome

an organism who's blastopore forms the mouth and their coelom forms from spilts in the mesoderm

- cleavage is spiral and determinate

- early embryonic cells are fated to become certain body parts

spiral cleavage

cleavage planes of cell division are diagonal to the vertical axis of the embryo

deuterosome

an organism who's blastopore forms an anus and the coelom forms from mesodermal outpockets of archentron (budding)

- cleavage is radial and indeterminate

- any cell can become a complete organism

radial cleavage

cleavage planes are either parallel or perpendicular to the vertical axis of the embryo

body plan

the general structure of an animal; the arrangement of its organ systems and the integrated functioning of its parts

radial symmetry

body plan in which body parts repeat around the center of the body

- usually sessile (attached) or planktonic (drifiting)

- no left and right sides nor front or back

- equips sea creatures with ability to experience environment equally from all directions

bilateral symmetry

body plan in which there exists two axes of orientation: front to back AND top to bottom

- usually have a "head" = concentration of sensory organs at the anterior plane (cephalization)

- have an active lifestyle

- animals have more specialization and complexity

body cavity

aka "coelom"

a fluid- or air-filled space between the digestive tract and the body wall

- allows internal organs to grow and move independently of outer body wall

acoelomate

an animal that lacks a coelom, or body cavity

pseudocoelomate

an animal whose body cavity is not completely lined by mesoderm

coelomate

animal with a body cavity located entirely within the mesoderm (BOTH the endoderm and ectoderm and lined by the mesoderm)

Hox genes

series of genes that controls the differentiation of cells and tissues in an embryo

- determine body plan, segmentation, as well as the number and placement of appendages

- duplicated in 4 clusters: A-D

choanoflagellates

protists that are the closest living relatives of animals

proterozoic (pre-cambrian) animals

Ediacaran biota (~565 mya)

-Earliest known animal fossils; many extinct

-Soft bodied: sponges, jellyfish-like, worm-like

paleozoic era animals

"Cambrian explosion" (~535 mya) - dramatic animal diversification:

-emergence of almost all major phyla (+ other extinct ones)

- first mineralized skeletons, shells

later paleozoic era

Era in which:

- vertebrate fishes dominate seas

- arthropods first invade land, followed by vertebrates (amphibians)

- emergence of first reptile-like amniotes

mesozoic era animals

Era in which:

- dinosaurs, pterosaurs, and aquatic reptiles roamed

- origin of birds and mammals

- saw the end of cretaceous extinctions

cenozoic era animals

era in which the diversification of modern groups occurred

deuterostomia, lophotrochozoa, ecdysozoa

what are the 3 major clades of bilaterian animals?

sponges

what branch on the animal phylogenetic tree is the sister group to all other animals?

eumetazoa

what clade on the animal phylogenetic tree encompasses animals that have tissues?

bilateria

what clade do most animal phyla belong to on the animal phylogenetic tree?