Animals

What are the four aspects that the origin and early evolution of animals was based on

Number of embryonic tissue layers, types of symmetry and degree of cephalization, presence/absence of a fluid-filled body cavity, how the embryo development proceed

Diploblasts

animals whose embryos have two germ layers (ectoderm- outside, endoderm-inside)

Triploblasts

animals whose embryos have three germ layers
The ectoderm, endoderm, and the mesoderm

What do the different layers in triploblast’s turn into

Ectoderm- skin and nervous system
Endoderm- lining of the digestive tract
Mesoderm- circulatory system, muscle, and internal structures

what are most cnidarians (jellyfish, corals, sea anemones) and ctenophores (comb jellies)

diploblastic

Why was the evolution of the mesoderm important

because it created the first complex muscle tissue used in movement

What do cnidarians and ctenophores have

nerve cells that organized into a nerve net

What do all other animals have but cnidarians and ctenophores

a centralized nervous system (neurons clustered into masses called ganglia)

Organisms with nerve nets have ____, Organisms with CNS have___

radial symmetry, bilateral symmetry

Most sponges are____

asymmetrical

What is a basic feature of a multicellular body

the presence or absence of a plane of symmetry

Animals with radial symmetry have___

at least two planes of symmetry

Animals with bilateral symmetry have____

a single plane of symmetry and long narrow bodies

What are radially symmetric organisms likely to do

encounter their environment in any direction, the nerve net can receive and send signals efficiently

Bilaterally symmetric organisms are likely to___

encounter their environment at one end, advantageous to have many neurons concentrated, with a nerve tract that carries info down the length of the body

What does bilateral symmetry allow for?

cephalization- the development of a head region where information processing, feeding, and sense are concentrated

Cerebral gangloin/brain

Large mass of neurons located in the head that is responsible for sending and receiving information to and from the body

Coelom

fluid-filled body cavity

Acoelomates

Triploblasts that do not have a coelom (no enclosed body cavity)

coelomates

triploblasts that have a coelom (enclosed body cavity completely lined with mesoderm) (openings)

Where does the coelom form

within the mesoderm and lined on both sides with cells from the mesoderm

What are the functions of the coelom in soft-bodies animals?

coelom creates a container for oxygen and nutrients and acts as an efficient hydrostatic skeleton, enabling movement without fins or limbs

Bilateria

except for adult echinoderms, all coelomates are bilaterally symmetric and have three embryonic tissue layers

Protosomes

when the mouth develops before the anus, and blocks of mesoderm hollow out to form the coelom

Deuterostomes

when the anus develops before the mouth, and pockets of mesoderm pinch off to form the coelom (chordates)

tube-within-a-tube design

when the outer tube forms the body wall and the inner tube forms the gut (worms)

Choanoflagellates

group of protists closest living relatives of animals

What were the first embryonic tissues to evolve, and which type of symmetry evolved first?

Endoderm and ectoderm, and radial symmetry evolved before bilateral

key aspect of cephalization

concentration of sensory organs in the head region

Four types of feeding structures

suspension, deposit, fluid, mass

what correlates closely with its method of feeding?

the structure of an animal’s mouthparts

Suspension feeders

capture food by filtering out particles in water or air ex. clams trap food particles in their gills

Deposit feeders

eat their way through a substrate, digest organic matter in the soil or sea floor ex. earthworms

Fluid feeders

suck or mop up liquids like nectar, have mouthparts that pierce a structure to withdraw fluids ex.butterflies

Mass feeders

take chunks of food into their mouths ex.horse

Three functions of movement

finding food, finding mates, escaping from predators

innovation of limbs

made highly controlled rapid movement possible

unjointed and jointed limbs

velvet worms (sac-like), crabs (precise movements)

When sexual reproduction occurs

fertilization may be internal or external

Three types of life stages

Larvae- look diff than adults, sexually immature
Juveniles- look and behave like adults, sexually immature
Adults- reproductive stage

metamorphis

a change from an immature body type to an adult body type

Proferia (sponges)

benethic- living at the bottom
systems of tubes and pores that create channels for currents
asymmetrical
specialized cell types, all sponges lack other tissue types

Cnidaria (jellyfish)

radially symmetric diploblasts
ectoderm and endoderm layers that sandwich a layer called mesoglea
specialized cells called cnidocytes used to capture prey
lifecycle of polp and medusa form

Medusea

move by jet propulsion caused by contraction of the bell structure (larvae swim by cilia)

Polyps reproduce asexually by

budding, fission, fragmentation

Both polyps and medusae are able to reproduce

sexually

Ctenophra (comb jellies)

gelatinous diploblasts
tentacles have cells containing adhesive which traps prey
move by cilia
male and female organs that undergo external self-fertilization