Comparing Evolutionary

Trends in Invertebrates and

Vertebrates(Chapters 29 + 33)

Body Symmetry Radial symmetry: extends from the

center outwards Ex:

Bilateral symmetry: sides are like mirror images (left and right) Ex:

Nervous System (Response)

Cephalization: concentration of sense organs and nerve cells in front (top) of the body

Evolution from ganglia (simple) to brain (complex)

Body Cavity coelom: area of body cavity between the

body wall and the digestive cavity Acoelomate: animal that lacks a body

cavity Ex: flatworm (planaria)

Pseudocoelomate: animal that has a partial body cavity Ex: roundworm (earthworm)

Embryo Development Depends on what the blastopore develops

into first… Protostome: mouth develops first

Ex: invertebrates Deuterostome: anus develops first

Ex: humans

Feeding and Digestion

Intracellular digestion: digestion occurs inside the cells Ex: sponges

Extracellular digestion: digestion occurs outside the cells in the digestive tract Ex: arthropods

Respiration (“Breathing”)

Gills: feathery structures that take in O2 from the water- usually close to the body surface Ex: fish

Alveoli: tiny air sacs at the end of the bronchiole that increase surface area and act in gas exchange Ex: humans

Vertebrate Introduction

Notochord: long supporting rod that runs below the nerve cord

Chordate: organism that has a dorsal nerve cord

Circulatory System Open system: blood is not always in

vessels Ex: insects, clams

Closed system: blood always in vessels Ex: humans

Excretion Roles:

control the output of waste products Involved in water balance

Movement and Support

Hydrostatic skeleton: move with water-filled cavity and accessory muscles Ex: jellyfish

Exoskeleton: external skeleton on outside of body Ex: insects

Endoskeleton: internal skeleton on inside of body Ex: kangaroo

Reproduction External fertilization: eggs fertilized outside

the body (ex: coral) Internal fertilization: eggs fertilized inside

the body (ex: humans) Oviparous: eggs develop outside the mother

(ex: snake) Ovoviparous: embryo gets nutrients from the

yolk of egg (ex: seahorses) Viviparous: embryo gets nutrients from mom

(ex: humans)

Regulating Body Temp.

Ectotherm: body temp determined by environment- organism must Ex: lizards

Endotherm: body temp controlled internally Ex: dogs

Reproductive Strategies

K selection: having only a few offspring but investing a lot of parental care into them Ex: humans, gorillas Occurs in crowded, competitive populations

r selection: having many offspring but investing very little parental care Ex: carp fish Occurs in populations that grow and

change rapidly