Chapter 7 Biology: Evolution, Animal Phyla, Symmetry, and Ecological Roles

Evolution

Change in heritable traits over time

Natural Selection

Process where individuals with advantageous traits survive and reproduce more

Microevolution

Change in allele frequencies within a population over time

Macroevolution

Large-scale evolutionary changes over long periods of time

Convergent Evolution

Unrelated organisms evolve similar traits due to similar environments

Adaptive Radiation

Rapid diversification of a species into different niches

Coevolution

Two species influence each other's evolution

Domain Eukarya

Organisms with cells that have a nucleus

Opisthokonta

Group that includes animals, fungi, and some protists

Porifera (Sponges)

Simple animals with no true tissues and no symmetry

Sponges Symmetry

Asymmetrical

Sponges Germ Layers

None

Sponges Feeding

Filter feeders

Sponges Function

Filter water and provide habitat

Cnidaria

Group including jellyfish, corals, and hydra

Cnidarians Symmetry

Radial symmetry

Cnidarians Germ Layers

Diploblastic (2 layers)

Cnidarians Special Feature

Cnidocytes (stinging cells)

Cnidarians Body Forms

Polyp (attached) and Medusa (free-swimming)

Cnidarians Function

Predators and habitat builders (coral reefs)

Platyhelminthes (Flatworms)

Flat, simple worms with bilateral symmetry

Flatworms Symmetry

Bilateral symmetry

Flatworms Germ Layers

Triploblastic (3 layers)

Flatworms Body Cavity

Acoelomate (no body cavity)

Flatworms Types

Planaria (free-living), flukes and tapeworms (parasitic)

Flatworms Function

Many are parasites

Germ Layers

Embryonic tissue layers that develop into body structures

Diploblastic

Two germ layers (ectoderm and endoderm)

Triploblastic

Three germ layers (ectoderm, mesoderm, endoderm)

Symmetry

Arrangement of body parts

Radial Symmetry

Body arranged around a central axis

Bilateral Symmetry

Left and right halves mirror each other

Asymmetry

No symmetry

Acoelomate

No body cavity between tissues and organs

Filter Feeder

Organism that feeds by filtering particles from water

Parasite

Organism that lives in or on a host and harms it

Habitat Provider

Organism that creates living space for other species (ex: coral)