bio 112 lecture 19: animal diversity 2

diploblastic animals

embryonically have two tissue layers:

1. sponges

2. cnidarians

3. ctenophores

sponges

simplest of living animals; contain three layers: epidermis (exterior protection), mesohyl (mid-layer), and choanocytes (interior)

cnidarians

common body plan with tentacles that surround a mouth; mouth leads to a gastric cavity and waste is excreted through the mouth

three layers: ectoderm, mesoglea (makes up the main structural parts of the organism), and endoderm

cnidarian specialized cells

1. epithelium: cells lining all body compartments

2. nerves: simple neural net (no brain)

3. light-sensitive cells (simple eyes)

4. pseudo-muscles: no true muscle cells, but they do have cells that allow for movement

5. rudimentary gonads

6. nematocysts: harpoon-like cells used for feeding that inject prey with toxin

ctenophores

no head, no real forward directionality, have simple stomach, move using the coordinated beating of cilia

protostome animals

embryonically have three tissue layers:

1. annelids

2. mollusks: gastropods, cephalopods, bivalves

3. nematodes

4. arthropods

annelids

bilaterally symmetrical segmented worms; cylindrical body with repeated segments

contain: true organs and muscles and organ systems (nervous, digestive, closed circulatory system, nitrogenous waste)

mollusks

have bilateral symmetry and animals with more complex organs

gastropods

marine, freshwater, and terrestrial

1. have modified coelom that has become small cavities around organs

2. move by a singular foot

3. evolved shells

4. have brains

cephalopods

1. intelligent predators with a unique body plan, have brain

2. jet propulsion system or siphon (move in the opposite direction of their head)

3. arms and tentacles to capture prey (helped gain speed when hunting)

bivalves

1. similiar anatomy to gastropods and cephalopods EXCEPT no head (and therefore no brain)

   1. still have a collection of internal organs and mouth

2. filter feeders (not as intelligent as gastropods and cephalopods)

nematodes

most numerous animals, microscopic, all internal organs are loosely stored in their body; has polysaccharide-rich cuticle that protects them

arthropods

most diverse phylum:

1. chelicerates

2. myriapods

3. crustaceans

4. insects

insects

1. desiccation resistant egges

2. wings

3. specialized respiratory system

4. metamorphosis

metamorphosis

major change from one developmental stage to another; separates life into eating stage and reproductive stage, and changes entire body plan to best accommodate both activities

respiration in insects

1. spiracles: pores in the exoskeleton

2. tracheae: internal system of tubes that directs oxygen and removes carbon dioxide

deuterostome animals

digestive tract builds itself from anus to the mouth:

1. hemichordates

2. echinoderms

3. chordates

hemichordates

acorn worms and pterobranchs

1. pharyngeal slits: function in feeding and respiration

2. dorsal nerve cord: ventral or lateral in all previously seen organisms

echinoderms

sea stars, urchins, sea cucumbers

1. water vascular system: permit bulk flow of oxygen and nutrients

2. tube feet: projection of water vascular system used for locomotion and feeding

3. pentaradial symmetry (and bilaterally symmetrical)

4. exoskeleton of porous calcite

chordates

1. cephalochordates

2. tunicates

3. vertebrates

defining chordate characteristics

1. pharyngeal slits (shared trait among all deuterostomes)

2. notochord: stiff rod of collagen along the back

3. neural tube: early feature of embryonic development; becomes dorsal nerve cord

4. myotomes: muscle segments

5. tail

cephalochordates

*has key chordate traits

1. lacks brain and eyes

2. no lateral appendages

3. no mineralized skeleton

tunicates

*has key chordate traits

1. adult filter feeding form only have pharyngeal slits

vertebrates

1. backbones

2. cranium, developed brain

3. eyes, mouth

4. internal skeleton

5. coelom

6. closed circulatory system

7. pharyngeal slits

fish

most diverse group of vertebrates:

1. jawless fish

2. cartilaginous fish

3. bony fish

   1. ray-finned fishes

   2. lobe-finned fishes

tetrapods

1. amphibians

2. reptiles

3. birds

4. mammals

amphibians

aquatic larval form; adult form with simple lungs; go from aquatic larval form to a terrestrial adult form

amniotes

includes:

1. reptiles

2. birds

3. mammals

*evolved amniotic egg (shelled egg) to reproduce without water

birds

1. evolved from dinosaur ancestors

2. lack teeth, scales —> feathers, hollow bones

3. circular breathing

mammals

covered in hair, produce milk to feed young:

1. monotremes

2. marsupials

3. placentals

monotremes

earliest group, lay eggs

marsupials

premature birth; mother keeps their young internally without an egg in a pouch (*lacks female reproductive system)

placentals

create temporary organ (placenta) to nourish the embryo (offspring are almost fully mature immediately after birth)