BIOL1020 - Week 12.2

types of symmetry in animals

• asymmetry: sponges

• radial symmetry: body around central axis (cnidarians)

• bilateral symmetry: left-right halves (most animals)

sponges

• no tissues or symmetry

• porous body, water flows through

• filter feeders

characteristics of cnidarians

• tentacles with stinging cells

• single opening

• gastrovascular cavity for digestion

• two tissue layers

bilateral symmetry

• one plane divides body into left/right halves

• has defined body axes

• enables movement and more complex body organizations

gastrulation

• early developmental process

• cells reorganize into layers

difference between diploblastic and triploblastic animals

• diploblastic: 2 layers (ecto- and endoderm)

• triploblastic: 3 layers (ecto-, meso-, and endoderm)

protostomes vs deuterostomes

• based on blastopore fate

• protostomes: blastopore → mouth

• deuterostomes: blastopore → anus

features of bilaterian animals

• triploblastic

• complex organ systems

• make up most animal species

lophotrochozoans

• major protostome group

• bilateral, triploblastic, complex systems

• enabled movement, feeding, gas exchange

key features of annelids

• segmented body

• well-developed head and nervous system

• more efficient feeding and movement

key features of mollusks

• mantle

• has shells

• found in aquatic and terrestrial environments

ecdysozoans

• has a cuticle

• must molt to grow

• protects from injury and drying

arthropods and major groups

• jointed legs

• chitin exoskeleton

• must molt to grow

• groups:

  • chelicerates

  • myriapods

  • crustaceans

  • insects

3 major deuterostome groups

• hemichrodates

• echinoderms

• chordates

key features of echinoderms

• radial symmetry

• calcium-based skeleton

• water vascular system

• tube feet for movement, feeding, gas exchange

vertebrates

• backbone

• internal skeleton

• cranium

key traits of amphibians

• tetrapods

• aquatic larvae, terrestrial adults

• require water for reproduction

• often use skin for gas exchange

amniotes

• amniotic egg

• protects embryo and prevents drying

• allows life fully on land

• no need for water for reproduction

key characeristics of mammals

• hair

• mammary glands (milk)

• types:

  • monotremes: egg-laying

  • marsupials: pouch

  • placentals: developed at birth