Ch 13 Animal Diversification

distinctions that divide animals

presence of tissue, symmetry, gut development, growth

sponges

only animal without true tissues and organs. Sessile except when larvae. Flagella creates water currents to bring in water through collar cells. Can reproduce sexually and asexually; asexually by budding

radial symmetry

many lines of symmetry; ex. jellyfish

bilateral symmetry

right-left side are mirror images

protostomes

animals who form the mouth first during embryonic development of the gut

deutrostomes

animals who form the anus first during embryonic development of the gut

molting growth

increase size by shedding an exoskeleton

continuous growth

increase size without molting

vertebrates

deuterostomes that have a backbone

invertebrates

no backbone, lungs, digestive system; makes up 97% of animals

Phylum Cnidaria

incl. jellyfish, corals, sea anemones

cnidarians

protostomes with radial symmetry, carnivores with stinging cells (cnidocytes) to capture prey.

Polyps (sessile) or medusas (mobile); or may have life cycles where both forms occur at different stages.

corals

live as small polyps in large colonial groups

coral reefs

assemblies of giant calcium carbonate skeletons

coral bleaching

when corals expel their zooxanthellae (algae) symbionts, causing them to lose color and turn white

sea anemones

have tentacles with cnidocytes surrounding the mouth. Free floating larval stage with mostly sessile adult polyps; no medusa stage

jellyfish

have tentacles with stinging cnidocytes

Phylum Platyhelminthes

incl. flatworms, tapeworms, flukes

flatworms

no body cavity, no digestive or circulatory systems. Attaches to intestines using scolex. Includes tapeworms and flukes.

tapeworms

a type of flatworm, but are always parasitic. Has long, flat bodies with repeated segments, acting as reproductive units.

Phylum Nematoda

incl. roundworms, nematodes

roundworms

unsegmented, have digestive systems, molts to grow

Phylum Annelids

segmented worms, earthworms, leeches

parasite

needs a host to survive

Phylum Mollusca

incl. gastropods, bivalves, cephalopods

gastropods

includes snails and slugs, making up 75% of mollusk diversity. Lives in both aquatic and terrestrial environments

bivalves

includes clams, scallops, oysters, mussels. Have a pair of hinged shells, aquatic only. Filter feeders; do not have radula (tongue)

cephalopods

includes squids, octopuses, nautiluses. Have tentacles with suckers for movement and hunting. Can change color, and are intelligent

Phylum Arthropoda

incl. insects, millipedes, centipedes, arachnids, crustaceans

insects

three pairs of walking legs, located on thorax. Most have wings

millipedes

long, segmented bodies with many pairs of walking legs, feeds on decaying plant materials.

centipedes

long, segmented bodies with many pairs of walking legs, and are predators with venom.

chelicerates

includes spiders, scorpions, ticks, etc. Have four pairs of walking legs with specialized feeding apparatuses called chelicerae.

crustaceans

includes shrimp, crabs, lobster, etc. Aquatic, and have five pairs of head appendages: 3 for feeding and 2 antennae.

metamorphosis

allows insects to grow despite having hard exoskeleton

complete metamorphasis

from larva, to pupa, to adult

incomplete metamorphasis

from nymph, to adult

echinoderms

includes sea stars, sea urchins, sea cucumber; are vertebrate’s closest invertebrate relatives

Phylum Chordata

incl. fish, birds, reptiles, primates, humans.

characteristics include: notochord, dorsal hollow nerve chord, gill slits, post-anal tail

chordates

deuterostomes with bilateral symmetry. The development of fins and jaws sets the stage for diversity among these vertebrates. Without fins, a tail is used to propel.

notochord

rod of tissue extending from head to tail

dorsal hollow nerve chord

extends along the back from head to tail, eventually forms spinal chord and brain

post-anal tail

all chordates have a tail in this location, but some, including humans, only have a tail during embryonic development

adaptations moving from water to land: respiration

solution: lungs

adaptations moving from water to land: gravity

solution: limbs and vertebrae

adaptations moving from water to land: egg dessication

solution: amniotic egg (waterproof, hard shell)

amphibians

lay soft eggs (non-amniotes) in water and usually have an aquatic juvenile stage with a terrestrial adult stage

reptiles

are tetrapod (four-limbed) amniotes, produce waterproof eggs

amniotic

hard shell, waterproof egg

non-amniotic

soft egg

birds

are endothermic with feathers to maintain body temperature

other reptiles

are ectothermic with scales

endothermic

warm-blooded

ectothermic

cold-blooded

mammals

are tetrapods with hair and milk producing mammary glands

monotremes

females lay eggs, produce milk, no nipples

marsupials

females give birth after short pregnancy; the young complete their development in the mother’s pouch. ex. kangaroos

placental mammals

females have a placenta that provides oxygen and nutrients to embryos. ex. humans

all genus “Homo” are extinct except Homo…

Sapiens

bipedalism

only use legs to walk, not all four limbs. This separates humans from other apes

tetrapods

four-limbed (NOT four-legged)