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