BIO182 Exam 3 Animal Review!

Describe the general features that characterize most animals.

• Multicellular eukaryotes lacking cell walls

• Nerves & muscles (except sponges)

• Heterotrophic: Carbon compounds from other organisms

• Most ingest food then absorb it

• Diversity of methods to obtain food (explains grave diversity)

Describe sponge organization and cell types.

Collar cells (choanocytes).

Outside layer of epidermal cells that regulate water flowing in/out with pores, where water enters through, then into chamber. Surrounding chamber is choanocytes, which beat fagellum & moves & draws water/nutrients into cavity to digest it. Sponges have spicules (sharp) for protection.

What are the general trends seen in the evolution of animals?

• Origin/elaboration of tissues

• Origin/elaboration of nervous system

  • Subsequent evolution of cephalized body (distinct head) & bilateral symmetry

• Evolution of a fluid: coelom (filled body cavity)

Porifera have no tissues

Ctenophora & cnidaria have 2 layer tissues (bony), no organs, radically symmetrical

The rest have 3 layer tissues, organs, & bilateral symmetry

Coelom

Fluid filled body cavity.

• Opening within mesoderm layer (on both sides)

• Compartment for circulation of O2 & nutrients

• Space for organs to move independently

Cnidarians & ctenophores don’t have a coelom

Most coelomic organicms are bilaterally symmetrical

Describe the basic body plan and diversity of Annelids (segmented worms)

Body Plan:

• Segmented: Repeated internal & external structures

• Head, body, & tail regions

• Complete digestive system

• Closed circulatory system

• No well developed respiratory system (uses diffusion)

Diversity: ~22k species

2 classes: Polychaetes vs Oligochaetes

• Based on bristle #

• Marine, freshwater, terrestrial (leeches ex)

Describe the basic body plan and diversity of Molluscs

Body Plan:

• Diverse anatomy

• Main locomotory structure is a muscular foot

• Organs found in “visceral mass”

• Mantle: Layer overlying visceral mass (secretes shell)

• Respiration through gills

• Radula: Feeding structure

Diversity (2nd most): ~100k species mostly marine (25% of all marine species), freshwater, terrestrial

8 monophyletic classes (unclear relationships): Chitons, Bivalves, Gastropods, & Cephalopods

Describe the basic body plan and diversity of Arthropods

Body Plan:

• Diverse anatomy

• Segmented body plan

• Jointed appendages

• Exoskeleton - chitin (growth by molting)

• Fused body regions (cephalothorax, abdomen) (head, thorax, abdomen)

• Respiration through gills or spiracles/trachea

• Central body cavity (hemocoel)

Diversity: ~1.134 million species - marine, freshwater, terrestrial (flying)

5 subphyla: Chelicerata (75k species) - horseshoe crabs, spiders, scorpions, etc. Myriapoda (16k species) → milipedes, centipedes, etc. Crustacea (70k species) → crabs, lobsters, crayfish, etc. Hexapods (rest of species) → insects

Deuterostomes

2 lineages: Enchinoderms (seastars) & chordata (mammals)

Synapomorphies: Pattern of early cell division. Mouth formation. Coelom formation. Endoskeleton

Describe the basic body plan and diversity of Echinoderms

Body Plan:

• Symmetry

  • Pentanadial as adults, bilateral as larvea

• Body secretions

  • Gonads & digestives glands

• Water vascular system

  • Controls tube feet & respiratory exchange

• Digestive system

  • Stomach can be “everted: through mouth

Diversity: ~7k species - marines, bottom dwelling

5 classes: Asteroidea (sea stars) - thick arms. Ophiuroidea (brittle stars) - thin arms. Echinoidea (sea urchins & sand dollars) - no arms. Crinoidea (sea lilies or feather stars) - feathered arms. Holothuroidea (sea cucumbers) - bilateral.

What are the 4 main characteristics of chordates?

• Notochord - Flexible support rod (muscle attachment)

• Dorsal Hollow Nerve Cord (brain & spinal cord)

• Pharyngeal slits/clefts (feeding/respiration)

• Post-anal tail (locomotion)

May be lost in adult stage

Cephalochordates

Not vertebrate but chordata

All chordate features in adults. Notochord extends to tip of head. Similar organisms found in Burgess shales (Pikeala). Filter feeding.

Urochordates

Tunicates. Not vertebrate but chordata

Surrounded by outer layer (tonic) as adults. Usually sessile (don’t move). Only chordata features in adults is pharyngeal slits (feeding). All features present in larval stage.

What new features are found in vertebrates that are not found in other chordates?

Vertebral column replaces notochord cranium (well developed braincase)

Describe the basic body plan and diversity of fishes

Most diverse group of vertebraes (31k species)

Agnathans: Jawless fishes (hagfishes & lampreys)

Grathostomes: “Jaw fishes” (sharks, skates, rays, ~1k species)

• fishes & their decendants

• Chondrichthytes (cartilaginous)

• Osteochthytwa (bony)

Actinopterygil (ray-finned) (most fishes, 50% of vertebraes)

Sarcopterygii (lobe-finned) (Ancestors to tetrapods)

Tetrapods

4 footed

• Muscular limb digits

• Joints (at least ancestrally)

• Limbs lost in some (lots)

• Major shift is to terrestrial environment

  • Support against force of gravity (repositioning limbs changes to skeleton)

• Changes to respiratory mechanisms

  • Protection against desiccation (skin barrier, protection of embryo)

Tetrapod Species

Amphibians (4k species): Frongs, salamanders, caeciliions. More dependent on water.

Repitles (non avian) (6k species): Turtles, lizards, snakes, crocodylians

Birds (avain reptile) (8.7k species): 4 chambered heart & endothermic (“warm blooded”)

Mammals (45k species)