BIO Lec. 14 - animal diversity

The Kingdom Animalia shares a common ancestor with ___.

a flagellated protozoan (Choanoflagellate)

Choanoflagellate

similar to a type of sponge cell

3 Main Traits of Animals:

1) Multicellular body plan

2) Chemoheterotrophic

3) Diploid form dominant

1) Multicellular Body Plan

• via specialization of cells

• nervous and muscle tissue (only in animals)

• no cell walls

2) Chemoheterotrophic

ingest food

3) Diploid form dominant…

gametes the only haploid stage

6 Major Innovations

1) Embryonic germ tissue

2) Body Symmetry

3) Gut

4) Body Cavity (coelom)

5) Segmentation

6) Cephalization

Embryonic germ tissues

(0, 2, 3)

(ecto-, meso-, endoderm)

Body Symmetry

none, radial, bilateral

Gut

none, incomplete, complete

Body Cavity (coelom)

fluid filled space

• none, pseudocoelom, coelom

Segmentation

none, present, present with fusion

Cephalization

increased development of head

Sponges (Porifera)

very simple animals

• no germ cell layers.

• no body symmetry (usually).

• no true tissues or organs - just a few cell types.

Porifera

Sponges:

• choanocytes cells -create water flow & filter food

• spicules - internal spines for protection

Choanocytes cells

create water flow & filter food

Spicules

internal spines for protection

Nearly all animals have ___ or ___ symmetry

radial or bilateral

Radial Symmetry

animals move slowly, if at all.

Bilateral Symmetry

• more rapid movement

• sensory organs concentrated at head

Cnidarians

jellyfish, corals, anemones

(slightly more complex animals)

Cnidarians Traits

• radial symmetry

• two germ cell layers

• true tissues

• gut with one opening

Cnidocytes/ nematocysts

stingers on tentacles - used for food capture and defense

Cnidarian life cycles

sessile polyp stage (e.g. anenome, corals)

+

free-swimming medusa stage (e.g. jellyfish)

Cnidarian life cycle: polyp & medusa stage

Traits of Animals with 3 Germ Cell Layers:

usually bilaterally symmetrical and 1 of the following:

• No body cavity: acoelomates

• Body cavity: pseudocoelomates, coelomates - most animals

Acoelomates

• no body cavity

• flatworms

Pseudocoelomates

• body cavity

• roundworms

Coelomates

• body cavity

• most animals

Coelom (Body Cavity) Advantages:

Movement -

• more flexible.

• hydrostatic skeleton.

Space - enables organ growth (ovaries).

Size - can increase as more surface area for cellular exchange.

Types of Acoelemates

• flatworms = Platyhelminthes

Many species are parasites:

• Flukes

• Tapeworms

Flatworms

• no body cavity

• bilateral symmetry

• some organs

Pseudocoelomates

has a body cavity

Types of Pseudocoelomates

Roundworms = Nematoda

Many are parasites.

• human roundworm

• pinworm

• hookworm

Two Forms of Coelomate Animals:

(grouped based on how body cavity forms)

1. “Protostomes” - blastopore = mouth

2. Deuterostomes - blastopore = anus

Benefit of segmented bodies

improved locomotion

Segmented worms

Segmented worms = Annelida

• earthworms

• leeches

• bristle worms

Segmented Mollusca

clams, snails, octopus...

• evolved from segmented ancestors.

• body plan: foot, mantle, and visceral mass.

Mollusc body plan

Yields a diverse array of animals (superficially appear very different from one another)

Nematoda *

trichinella worm (pork)

• 1 dorsal nerve, 1 ventral nerve

Arthropods w/ Segmented External Skeletons

Insects, spiders, crabs, millipedes

• Secreted body surface thickened & rigid (protein and chitin) = exoskeleton

Exoskeleton

Major innovation for animals.

• growth by periodic molting (shedding) of exoskeleton.

• muscle attachment site

• strong

• waterproof

5 Groups of Arthropods

• Trilobites: all extinct

• Arachnids and relatives: scorpions, spiders, ticks, horseshoe crabs...

• Crustaceans: lobsters, crabs, barnacles, sowbugs

• Insects – this group has the greatest number of species of any animal group!

• Centipedes, millipedes

True or False: Barnacles are mollusks

False

How do you tell if your “bug” is really an insect?

• three body regions (two)

• single pair of antennae (two or none)

• three pairs of legs (four or more)

Echinoderms examples *

• sea stars, urchins, sand dollars, sea cucumbers etc.

Echinoderms Features

• radially symmetrical body plan as adults (but immatures bilateral!)

• water vascular system

• calcified internal skeleton (most)

True or False: Protosomes are monophyletic

False

Chordate characteristics

• Pharyngeal slits as feeding devices – modified as gills later

• Notochord - supporting rod for better wiggle movement or swimming

• Post-anal tail

Why do sea squirts or tunicates move?

(larval stage mobile - like lancelet).

• adults are sessile filter feeders

Lancelets

has not changed much from early chordates— a filter feeder.

• (early vertebrates filtered small animals from mud)

Origin of Vertebrates: Craniates charactieristics

• Jointed internal skeletons around a vertebral column

• Rigid skeleton more support for rapid swimming.

What craniates do NOT have a jointed internal skeleton around a vertebral column?

hag fish

Obtaining O2 from air: Fish examples

• Jawless fish – lampreys (38 spp) + hagfish (20 spp)

• Cartilaginous fish - sharks, rays, chimeras (850 spp)

• Bony fish - bass, trout...(ray-finned and the lobe-finned fish and lungfish) (28,000 spp)

Where did fish jaws evolve from?

anterior gill arches

Fish Evolution to Amphibians

1. Fishes

• Fins (first unjointed) - control swimming movement, provided stability in water.

2. Three fish lineages evolved jointed fins (~limbs?)

3. Amphibians (first terrestrial vertebrates) arose from one of these lineages.

• Limbs – enabled the first amphibians to move quickly and precisely on land

Amphibians, the first terrestrial vertebrates, arose from ___.

a lineage of fish with jointed fins.

• ex: Tiktaalik: many toes

Amphibian lungs evolve for ___.

land respiration

Amphibian species

• caecilians — (caecilian - giving birth)

• frogs and toads

• salamanders

Chytrid fungus

eradicated more than 100 frog species across the globe; spread to an ecosystem in Panama

Amniotes

vertebrates completely independent of water for reproduction

Why do amniotes not need water to reproduce?

• Amniotic egg: water-impermeable egg shells to keep embryo wet.

• Internal fertilization

• Water-proof skin

What animals are included in the 7000 reptile species on Earth?

• turtles and tortoises

• tuataras

• snakes and lizards

• crocodilians

There are 9,234 bird species. What characterizes them all?

feathers

Why are reptiles a poorly-defined group? *

They do not include birds, which would make them monophyletic.

There are 4,500 mammal species. What characterizes them all?

• hair

• suckle young with mammary glands

What are the 3 groups of mammals?

1. Monotremes – 5 spp.

2.  Marsupials - 260 spp.

3.  Eutherians/Placentals - 4,350 spp.

Monotremes

• Egg laying mammals

  • Spiny Anteaters or Echidnas

  • Platypus

Marsupials

• Give birth to tiny undeveloped young

• Have pouch for young

Eutherians (Placentals)

• Give birth to relatively well-developed young

  • Bats: ¼ of all mammal species

  • Rodents: ½ of all mammal species

All primates were ancestrally:

• arboreal

• insectivores

Hominids evolved in Africa from ___, ___ ancestors *

terrestrial, bipedal

True or False: Tuatara are lizards *

False