BSC 116 Exam 3

Definition of an animal

Multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers

Animals are

multicellular eukaryotes

Animals cells are supported by

collagen

Most animal cells also have

muscle cells and nerve cells

Most animals have tissues

groups of similar cells that act as a functional unit

Asexual reproduction is limited to a few groups

budding, fission, parthenogenesis

Sexual reproduction is the norm

diploid stage usually dominating the life cycle

Sexual reproduction typical

diploid adults produce haploid gametes

zygote develops into

gastrula

cleavage

cell division without growth

blastula

hollow balls of cells with an internal cavity: blastocoel

gastrulation

invagination of blastopore to form the beginning of the gut

sponges lack

tissues; cells can de-differentiate into other cell types

other animals go through gastrulation

invagination to form blastopore (becomes mouth or anus) and archenteron (gives rise to the gut)

endoderm

tissue lining gut

ectoderm

outer layer of cells; skin and nervous system

diploblasts

only two tissue types; basically a fancy gastrula

e.g., jellyfish, sea anemone

triploblasts

have a third germ layer - mesoderm

direct devolopment

offspring looks like a little version of the parent

indirect development

young offspring (larvae) morphologically/ecologically different than the adult

animals are most closely related to colonial opithokont group called

choanoflagellata; have cells similar to a feeding cell type used by sponges

neoproterozoic era

1 billion to 541 mya

earliest large animal fossiles

ediacaran biota

Paleozoic era (541-252 mya)

cambrian explosion: “rapid” appearance in the fossil record of most animal phyla: bilaterians

Mesozoic era (began 252 mya)

age of the dinosaurs: end - cretaceous extinction wiped out dinosaurs

cenozoic era (began 65 mya)

modern era

do animals have specific body plans?

yes

what three aspects of body plans are we interested in?

symmetry, tissue organization, and body cavities

what symmetry do sponges have

asymmetry

what symmetry do sea anemones have

radial symmetry

what symmetry do most animals have

bilateral symmetry - dorsal, ventral, anterior, posterior

cephalization

having a front end (head) typical of animals that move under own power

coelom

fluid filled body cavity

coelomates

body cavity lined with mesoderm

pseudocoeloomates

not completely lined with mesoderm

acoelomates

lack a body cavity

fluid filled body cavity serves as a

hydrostatic skeleton to antagonize muscles

protostomes

solid masses of mesoderm form; expand to filled blastocoel

deuterostomes

mesoderm buds of endoderm of archenteron

difference in early zygote cleavage between protostomes and deuterostomes

protostomes: determinate spiral cleavage

deuterostomes: indeterminate radial cleavage

difference in gut development in protostomes and deuterostomes

protostomes: blastopore becomes the mouth

deuterostomes: blastopore becomes anus

invertebrates

animals that lack a backbone, accounts for over 95% of known animal species

Porifera

sponges

Ctenophora

comb jellies

Cnidaria

jellyfish, sea anemones, coral

Bilateria

animals with bilateral body symmetry

most sponges are

hermaphrodites: same individual makes sperm and eggs

sponge body organized like a perforated vase

many small spores (ostia) leading to a big open internal space (spongocoel), with a big top opening (osculum)

Suspension feeders

filter/capture food particles from the water

the mesohyl separates the

inner and outer layers of cells

amoebocytes move:

food around

hydrozoa

hydroids, hydromedusae, siphonophores

anthozoa

anemones, corals, sea fans, and sea pens

scyphozoa

jellyfish

cubozoa

box jellies

staurozoa

stalked jellies

life cycle of class hydrozoa

alternates between medusa and polyp phases

life cycle of classes scyphozoa and cubozoa

jellyfish and box jellies; polyp stage small relative to medusa

life cycle of class anthozoa

sea anemones, corals; medusa stage lost, solitary or colonial

diversity of cnidaria

hydrozoa, anthozoa, scyphozoa, cubozoa, staurozoa

main groups of bilateria

protostomia (lophotrochozoa, ecdysozoa), deuterostomia

Phylum platyhelminthes

flatworms

phylum annelida

segmented-worms

phylum mollusca

mullusks

some taxa have ciliated trochophore type larvae

platyhelminths, annelida, mollusca

some taxa have a feeding structure called a lophophore

ectoprocta, brachiopoda

phylum ectoprocta

bryozoans

phylum brachiopoda

lamp shells

phylum rotifera

lacking both: rotifers

acoelomates

flatworms generally long and flat; most are hermaphrodites (both male and female)

acoelomates lack

gastrovascular cavity

Main groups of flatworms

turbellaria, monogenea, tremotada, cestoda

class turbellaria

planarians; mostly free living

classes monogenea and tremetoda

flukes; parasites

class cestoda

tapeworms; intestinal parasites

diversity of annelida

polychaeta, oligochaeta, hirudinea

Class polychaeta

mostly marine, also freshwater; have lateral parapodia for locomotion

class oligochaeta

earthworms; mostly terrestrial and freshwater

class hirudinea

leeches; mostly freshwater; blood parasites

diversity of mollusca

polyplacophora, gastropoda, bivalvia, cephalopoda

Class polyplacophora

chitons

Class gastropoda

snails, slugs

class bivavlia

clams, mussels, oysters, and scallops

class chepalopoda

squid, octopus, nautilus

chaaracteristics of mollusca

calcium carbonate shell, radula (toothed tongue like organ), foot for crawling, organs concentrated into visceral mass, mantle cavity (space under mantle), gonochoristic (separate sexes)

lophophorates

ectoprocta and brachiopoda

Phylum ectoprocta

bryozoans (“moss animals”)

Phylum brachiopoda

lamp shells; convergent morphology with bivalves

Ecdysozoa

phylum arthropoda and phylum nematoda

athropods are covered by a

jointed exoskeleton

major groups of arthropoda

trilobitimorpha, chelicerata (arachnids), myriapoda, pancrustacea (crustaceans, decapods, isopods, copepods, hexapoda)

Trilobitimorpha

extinct; paleozoic trilobites

chelicerata

arachnids: spiders, ticks, mites, scorpions

myriapoda

centipedes and millipedes

pancrustacea

custaceans, decapods, isopods, copepods, hexapoda

decapods

lobsters, crabs, shrimp, krill

isopods

pill bugs/rollie pollies

copepods

tiny, planktonic; barnacles

hexapods

insects and relatives

most species on earth are

insects