Chapter 32 Animal Diversity

Bio 202

What are animals?

Multicellular, heterotrophic eukaryotes that ingest their food

What type of cells do animals have?

Eukaryotic cells without cell walls

What does heterotrophic mean?

Must consume other organisms for energy

What protists are the closest living relatives of animals?

Choanoflagellates

What evidence links choanoflagellates to animals?

Genes for cell adhesion and cell signaling

When did the Cambrian Explosion occur?

~541–485 million years ago

Why was the Cambrian Explosion important?

Most modern animal phyla appeared rapidly

What is a synapomorphy?

shared derived trait that defines a clade

Name four defining synapomorphies of animals

Multicellularity, heterotrophy, specialized cells, embryonic development

What embryonic stages do animals undergo?

Cleavage → blastula → gastrulation

What is the Linnaean classification system?

Hierarchical system grouping organisms by shared traits

What are the levels of Linnaean classification?

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

What is binomial nomenclature?

Two-part scientific naming system (genus + species)

What is asymmetry?

No plane of symmetry

Which animals are asymmetrical?

Sponges

What is radial symmetry?

Body parts arranged around a central axis

Which animals have radial symmetry?

Cnidarians and ctenophores

What is bilateral symmetry?

One plane of symmetry with left and right sides

Which animals have bilateral symmetry?

Most animals (Bilateria)

What are germ layers?

Embryonic tissue layers

What are the three germ layers?

Ectoderm, mesoderm, endoderm

What animals are diploblastic?

Cnidarians and ctenophores

What animals are triploblastic?

Bilaterians

What does the ectoderm form?

Skin and nervous system

What does the endoderm form?

Digestive tract lining

What does the mesoderm form?

Muscles, circulatory system, internal organs

What is a coelom?

Fluid-filled body cavity fully lined with mesoderm

What is an acoelomate?

Animal with no body cavity

What is a pseudocoelomate?

Body cavity partially lined with mesoderm

What is a coelomate?

Body cavity completely lined with mesoderm

What are advantages of a coelom?

Organ protection, circulation, hydrostatic skeleton

What is a protostome?

Blastopore becomes the mouth

What cleavage pattern do protostomes have?

Spiral cleavage

Name examples of protostomes.

Arthropods, mollusks, annelids

What is a deuterostome?

Blastopore becomes the butt

What cleavage pattern do deuterostomes have?

Radial cleavage

Name examples of deuterostomes.

Echinoderms and chordates

What are Porifera?

Sponges

Key characteristics of sponges?

Asymmetrical, no true tissues, filter feeders

What are cnidocytes?

Specialized stinging cells in cnidarians

What body forms do cnidarians have?

Polyp and medusa

What are ctenophores commonly called?

Comb jellies

What is cephalization?

Concentration of sensory organs and neurons in the head

Which animals have nerve nets?

Radially symmetric animals

Which animals have a central nervous system?

Bilaterally symmetric animals

What are the four animal feeding strategies?

Suspension, deposit, fluid, mass feeding

What is a suspension feeder?

Filters food from water or air

What is a deposit feeder?

Eats organic matter in substrate

What is a fluid feeder?

Sucks liquids from food source

What is a mass feeder?

Eats large pieces of food

What is metamorphosis?

Change from larval to adult body form

What is the difference between oviparous and viviparous?

Oviparous lay eggs; viviparous develop internally

What are the three life stages of animals

Larva, juvenile, adult

What early traits define animal phyla?

Symmetry, germ layers, coelom, embryonic development

What drives diversification within phyla?

Adaptations for sensing, feeding, movement, and reproduction

Are most animals vertebrates or invertebrates?

Invertebrates