Chapter 29 BIO

Multicellularity

Made of many cells

Heterotrophic metabolism

Cannot make own food; must consume other organisms

Internal digestion

Food is broken down inside the body

Movement

Ability to move at some life stage

Nervous systems

Cells that coordinate responses to stimuli

Are these traits universal

No, but gene sequencing shows animals are monophyletic

Extracellular matrix

Network outside cells that supports structure

Collagen

Structural protein in animal tissues

Proteoglycans

Molecules that help support and hydrate tissues

Cell junctions

Connections between cells

Tight junctions

Prevent leaks between cells

Desmosomes

Hold cells together

Gap junctions

Allow communication between cells

Hox genes

Control body plan development and support shared ancestry

Embryonic tissue layers

Layers formed early in development

Ectoderm

Outer layer (skin, nervous system)

Endoderm

Inner layer (digestive system)

Mesoderm

Middle layer (muscles, organs)

Diploblastic

Two layers (ecto + endoderm)

Triploblastic

Three layers (ecto + mesoderm + endoderm)

Monoblastic

No true tissues (sponges)

Blastopore

First opening in embryo

Protostome

Blastopore becomes mouth

Deuterostome

Blastopore becomes anus

Bilaterians

Animals with bilateral symmetry

Body plan

General structure and arrangement of organ systems

Five body plan features

Symmetry, body cavity, segmentation, appendages, nervous system

Symmetry

Ability to divide into similar halves

Asymmetrical

No symmetry (sponges, placozoans)

Radial symmetry

Arranged around central axis (cnidarians, ctenophores)

Bilateral symmetry

Mirror halves along one plane

Anterior

Head end

Posterior

Tail end

Dorsal

Back side

Ventral

Belly side

Body cavity

Space where organs develop and are housed

Segmentation

Body divided into repeating units

Segmentation benefit

Allows specialization and precise movement

Arthropod success

Due to modifications of segmented body plan

Segmentation visibility

May not always be visible externally

Appendages

External body structures

Locomotion

Movement to find food, mates, avoid predators

Echinoderm movement

Tube feet used for movement

Jointed limbs

Found in arthropods and vertebrates

Appendage functions

Movement, sensing, feeding, reproduction

Antennae

Sense environment

Claws/mouthparts

Capture or chew food

Reproductive appendages

Transfer sperm or incubate eggs

Wings evolution

Limbs modified into wings in insects, birds, bats

Motile animals

Move to find food

Sessile animals

Stay in one place and bring food to them

Feeding strategies

Vary widely and can change during life cycle

Herbivores

Eat plants

Herbivore digestion

Long, complex digestive systems

Plant defenses

Tough tissues and chemicals require detoxification

Predators

Capture and consume prey

Predator adaptations

Sharp teeth, claws, strong senses

Predator strategies

Stalk prey or ambush

Omnivores

Eat both plants and animals

Diet shift

Some animals change diet during life stages

Parasites

Live on or in a host

Parasite size

Usually smaller than host

Parasite effect

Usually do not kill host

Parasite life cycles

Often complex

Endoparasites

Live inside host, may lack digestive system

Ectoparasites

Live outside host, pierce or suck fluids

Detritivores

Feed on dead organisms and waste

Detritivores role

Recycle nutrients into ecosystem

Life cycle

All stages from embryo to adult

Direct development

Young resemble small adults

Indirect development

Larval stage very different from adult

Larva

Immature stage specialized for feeding/dispersal

Egg energy trade

off - More energy = longer development

Altricial

Helpless young requiring care

Precocial

Independent young able to move/feed early

Trade

off - Benefit in one area results in cost in another

Bilaterian synapomorphies

Bilateral symmetry, triploblasty, central nervous system

Nonbilaterians -

Sponges, cnidarians, ctenophores, placozoans

Sponges (Porifera)

Simplest animals with ~8,500 species

Sponge tissues

No true tissues or organs

Specialized cells

Present but not organized into tissues

Spicules

Structural skeletal elements

Silica spicules

Found in glass sponges and demosponges

Calcium carbonate spicules

Found in calcareous sponges

Sponge habitat

Mostly marine

Sponge feeding

Filter feeding

Water canal system

Network that moves water through sponge

Choanocytes

Flagellated cells that draw water and capture food

Cnidarians

Jellyfish, corals, sea anemones (~12,500 species)

Cnidarian habitat

Mostly marine

Functions

Digestion, circulation, gas exchange, support

Blind sac

One opening serves as mouth and exit

Cnidarian life cycle

Often has polyp and medusa stages

Polyp

Sessile form

Anthozoans

Corals, sea anemones, sea pens

Sea anemones

Solitary

Sea pens

Colonial with specialized polyps

Primary polyps

Anchor organism

Secondary polyps

Feeding structures

Corals

Sessile colonial cnidarians