1. 23 Invertebrate Diversity *95% all animals are invertebrates!

2. 23.1 Animal Characteristics
Animals are the most physically diverse kingdom
Eukaryotic: single or multicellular
Vary in size from microscopic (rotifers) to 25ft (blue whale)
Some appear simple while others have complex structures
Found every place on earth
Heterotophs: herbivores, predators, and detritivores
Walk, swim, borrow, fly, or sessile

3. Animal Characteristics:
Multicellular Heterotrophs
Hetero = different, trophos = feeder
All animals need nutrition (cannot photosynthesize)
Uses cellular respiration in mitochondria to make ATP
Eukaryotes with specialized cells/ tissues/ organs
Share heterotrophic ancestors with fungi (also multicelluar heterotrophs)
Cells Supported by Collagen
Lack cell walls like plants
Collagen: 3 strand protein in skin, bone, ligaments, fingernails, and hair; rope-like fibers that are strong and flexiable

4. Animal Characteristics continued:
Reproduce Sexually (usually)
Diploid parent makes diploid offspring (1 set genes from each parent)
Do not have a free-living haploid stage
Can reproduce asexually: budding, binary fission
Have Hox Genes
Homeotic genes that control early development
Every homeotic gene has sequence of 180 nucleotides is called homeobox or Hox genes
Define head and tail pattern of development in embryos

5. 23.2 Animal Diversity Each animal phylum has a unique body plan
Vertebrates have an internal segmented backbone.
Invertebrates do not have a backbone.
Invertebrates encompass most animal groups.

6. Differences in body plans result from differences in the expression of Hox genes.
Hox genes tell embryonic cells which body part to become.
Mutations in Hox genes led to the vast diversity of animal species.

7. Three criteria are used to categorize animals.
body plan symmetry
tissue layers
developmental patterns

8. There are two types of body plan symmetry.
bilateral symmetry: body divides equally along one plane
Have 3 distinct layers of tissue
radial symmetry: body arranged in circle around a central axis
Only have 2 layers of tissue
Tissue layers:
both animal types have ectoderm and endoderm
bilateral animals have mesoderm

9. Animals are divided into two major groups, the protostomes and the deuterostomes.
Protostomes form mouth-first, and anus second.
Deuterostomes first form the anus and then the mouth.

10. Structures and genetics gives evolutionary history
Protostomes and deuterostomes are the two major radiations on the animal phylogenetic tree.
The current organization of the animal kingdom shows some unexpected relationships.
Technological advancements help to clarify evolutionary relationships

11. 23.3 Sponges and Cnidarians **Simplest animals!
Sponges have specialized cells but no tissues
Sponges are the most primitive animals on Earth.
570 million-year-old fossils
closely related to group of protists
Sponges share common characteristics.
sessile
reproduce both sexually (swimming larva) and asexually (budding)
filter feeders

12. Sponges have several types of specialized cells.
Pinacocytes: thick and leathery, outer layer
Choanocytes: “collar cells,” iner layer of sponge
Amoebocytes: mobile cells in between 2 layers, absorb/digest/ move nutrients

13. Cnardians are oldest animals with specialized tissues!
Cnidarians have two body forms.
polyps
medusas
Cnidarians are made up of two tissue layers separated by mesoglea.
The outer tissue layer has three cell types.
contracting cells
nerve cells
cnidocytes (which contain nematocysts)

14. The four major cnidarian classes are defined by their dominant body form.
Anthozoans such as sea anemones have a dominant polyp stage, corals or sea anemones.
Hydrozoans such as hydra alternate between forms.
Scyphozoans are jellyfish with a dominant medusa form.
Cubozoans such as sea wasps or box jelly have a dominant medusa form.

15. 23.4 Flatworms, Mollusks, and Annelids
Flatworms are simple bilateral animals
Flatworms have a solid body and incomplete or absent gut.
There are three classes of flatworms.
Planarians
Flukes
Tapeworms

16. There are three classes of flatworms.
Planarians: non-parasitic flatworm, head with eyespot and simple brain of nerve clusters, ventral mouth, use chemoreceptors to hunt, move with cilia and muscles
Flukes: parasitic flatworm, mouth with pharynx, life cycles with multiple hosts, ex Schistosoma from larva in water, causes fever and muscle pain of host
Tapeworms: parasitic flatworms, live in gut of host, head with hooks to attach to host, ribbonlike body with no gut, absorbs nutrients from host, complex life cycles with multiple hosts; ex tapeworm from eating infected flea

17. Mollusks are diverse animals
Mollusks and other bilateral animals have a complete digestive tract.
A complete digestive tract has two openings: a mouth and an anus.
Flatworms are the only bilateral animals without a complete digestive tract.
Mollusks share at least one of three features.
Radula: file-like feeding organ
Mantle: tissue covering internal organs
Ctenidia: flat gills in pocket of mantle

18. Classes of Mollusks
Gastropoda: snails, nudibranches, abalones, and limpets
Pelecypoda (bivalves): clams, oysters, mussels, and scallops
Cephalopoda: Squid, octopus, nautiluses, and cuddlefish
Scaphopoda: trunk shells
Polyplacophora: chitons
Alacophora: worm-like, unlike rest of classes
Trybidia: believed to be extinct until 1952, live very deep/ little known

19. Mollusks have a variety of reproductive strategies.
Most strategies involve sexual reproduction.
Some species are hermaphrodites.

20. Annelids' have segmented bodies
Segmentation refers to the repeated sections of an annelid’s body.
The coelom is a fluid-filled space completely surrounded by muscle.
There are three groups of annelids.
Earthworms: eat organic waste make castings
Marine worms: like earthworms
Leeches: eat inverts or suck blood

21. 23.5 Roundworms Roundworms shed stiff outer skeleton as they grow
Roundworms are protostomes with bilateral symmetry.
Roundworms have a tough outer skeleton called a cuticle.
made of chitin
must be shed to grow
Roundworms have a pseudocoelom, not completely lined by muscle.
Roundworms reproduce sexually.

22. Nearly every plant and animal species are parasitized by roundworms.
Hookworms: in digestive tract/ feeds on blood, feet on contaminated soil causes 1 billion people to be infected! (tropics/subtropics)
Pinworms: in gut, often accidentally ingested
Guinea worms: in guts/ connective tissues, from drinking contaminated water

23. 23.6 Echinoderms
Echinoderms are same evolutionary branch as vertebrates!
Echinoderms have radial symmetry.
Echinoderms have an internal skeleton made of interlocking ossicles.
Echinoderms have a water vascular system.
a series of water-filled ring canals around central disk
canals store water used for circulation and movement
changes in water pressure extend and retract tube feet

24. Echinoderms have a complete digestive system.
Some echinoderms can regenerate limbs or other body parts.
Most echinoderms reproduce sexually.

25. Classes of Echinoderms
Crinoidea: Feather Stars and Sea Lillies
Sessile, can move arms, feed using tube-feet
Asteroidea: Sea Stars
Filter-feeders or carnivorous
Ophiuroidea: Brittle Stars and Basket Stars
Mobile/ quick, scavengers or predators
Echinoidea: Sea urchins, Sea Biscuits, and Sand Dollars
Sea urchines graze
Biscuits and dollars move/ burrow
Holothuridea: Sea Cucumber
Fleshy with thick tennicles