Animal Evolution and Body Plans

• Animals are defined by multicellularity via eukaryotes, lacking cell walls, ingesting prey, and having the ability to move

Hox Genes

• Regulate development and body plans
• Determine where body parts form
• Processed by bilaterally symmetrical animals

Forms of Symmetry

• Symmetry is related to animal movement and food sourcing
• Asymmetry lacks symmetry

Radial Symmetry

• The same all around, like a perfect pizza

Bilateral Symmetry

• Two-sided with left and right sides
• Has dorsal (top) and ventral (bottom) sides
• Includes anterior (head) and posterior (tail)
• Cephalization aids response to stimuli

Acoelomate Body Plan

• The simplest plan with no body cavity
• Bodies are solid between the digestive tract and body covering
• Exemplified by flatworms

Pseudocoelomate Body Plan

• A "fake" coelomate
• Organisms possess a body cavity that is not surrounded by mesoderm-derived tissues
• Contains blastocoel from the embryo
• Exemplified by roundworms

Coelomate Body Plan

• The most complex plan
• Organisms possess a true body cavity (coelom) completely surrounded by organs and tissues derived from the mesoderm
• Seen in annelids, mollusks, arthropods, echinoderms, chordates

Germ layers

• Ectoderm, endoderm, and mesoderm create different tissues in early embryos

Embryology

• Ectoderm covers the surface/outer covering and nervous system
• Mesoderm forms muscles, skeleton, kidneys, reproductive systems _ Endoderm forms endocrine glands, lungs, and the digestive tract

Structures, Concepts

• Sperm + egg = diploid zygote

Protostome

• Spiral cleavage where cell roles are determined early

Deuterostome

• Radial cleavage where cell roles are indeterminate until later
• Blastula is a hollow ball with fluid-filled cavity

Gastrulation

• Protostomes develop a mouth first
• Deuterostomes develop an anus first

Diploblastic Embryos

• A 2 layer system without mesoderm
• Have simple body plans
• Are typically radially symmetrical
• Examples are jellyfish, sea anemones

Triploblastic Embryos

• Contains mesoderm with 3 layers
• More complex body plans
• Are mostly bilateral
• Examples are humans, insects, worms, mollusks

Blastopore Fate

• In protostomes it becomes the mouth
• In deuterostomes it becomes the anus

Lophotrochozoans

• Have ciliated tentacles surrounding the mouth

Ecdysozoans

• Shed exoskeletons through ecdysis
• Examples are arthropods and nematodes

Invertebrate animals.

• Distinguishing diploblastic and triploblastic development
• Diploblastic contains 2 germ layers (endo and ecto derm)
• It is simpler with few tissues that includes jellyfish and corals
• Triploblastic contains 3 germ layers (endo, ecto, and mesoderm)
• It is more complex and includes flatworms, roundworms, arthropods mollusks and all mammals

Acoelomates

• No body cavity, space between body wall and digestive tract are filled with issues
• Includes Porifera, Cnidaria, Platyhelminthes

Pseudocoelomates

• Includes a body cavity what is not lined with mesoderm
• Body cavity is sandwiched between endoderm and mesoderm
• Nematoda

Coelomates

• Body cavity is lined with mesoderm and between the wall and digestive tract
• Includes Mollusca, Annelida, Arthropoda, Echinodermata

Gastrovascular Cavity

• One opening thats simple allowing food waste and intake
• Cnidarians

Alimentary Canal: Two Openings

• Allows for a one way flow of nutrients digestion which includes separate mouth and anus
• Cnidaria and Platyhelminthes

Protostomes Development

• A blastospore that develops into a mouth with cleavage that is spiral and determinant
• Coelom forms through schizocoely which includes Annelids, mollusks, Platyhelminthes, Nematoda, Arthropods

Deuterostomes

• A blastospore develops into anus with cleavage that is radial and indeterminate
• Coelom forms through entercoely

Coelom

• Aids complex organ development
• Protects organs
• Facilitates movement
• Supports independent movement of organs

Body Segmentation

• Provides flexibility in movement
• Body parts specialize for specific functions More efficient movement

Defining characteristics (Porifera)

• Includes sponges with: Multicellularity and cylindrical asymmetry with two body layers
• Choanocytes create water currents and line inner cavity
• Amoebocytes: transport nutrients
• Spicules are needle like skeletons
• Spongin is flexible

Defining characteristics (Cnidarian)

• Includes: Corals, sea anemones, jellyfish with: radial symmetry, no organs, and diploblastic activity
• Polyp: Tube-shaped and Attached to a surface for asexual and sexual reproduction
• Medusa: Bell-shaped floating for sexual spawning
• Epidermis is an outer layer
• Gastrodermis is an inner lining
• Mesoglea is jelly like in between dermis
• Cnidocytes are specialized
• Gastrovascular has a cavity with opening

Defining characteristics (Playthelminthes)

• Includes: Flatworms with: Bilateral symmetry, no coelomates, protostomes characteristics, a gastrovascular canal, and flame cells
• Flame cells function like a kidney to remove waste

Defining characteristics (Nematode)

• Includes: Roundworms and hookworms with: Bilateral symmetry, triploblastic characteristics, pseudocoelomates and protostomes characteristics,
• Hydrostatic aids support
• Have a complete alimentary canal and some cephalization

Defining characteristics (Mollusca)

• Includes: Clams, nails, squids, etc with: Bilateral symmetry, triploblastic characteristics, coelomates, protostomes characteristics
• soft body with hard shell
• Mantle is what covers the tissues and protects internal organs
• Radula is a tongue used for scraping food in the mouth
• Visceral aids organ clustering

Defining characteristics cont.

• Annelida aids segmented worms and bilateral symmetry that is triploblastic with coelomate and protostome characteristics
• hydrostatic skeleton and a complete alimentary canal with some cephalization
• Arthropoda which is Insects, crustaceans, millipedes, centipedes
• Bilateral symmetry that is Triploblastic with coelomate and protostome characteristics
• segmentation & a complete alimentary canal
• High cephalization

Echinodermata

• Contains star fish, sea urchins, sea cucumbers
• Bilateral then radial that is Triploblastic
• Coelomates with coelmates
• Contains Endoskeleton

Comparing and Contrasting animal phyla

• Proifera is neither with asymmetry characteristics. -Includes Acoelomates, Cnidaria
• Radial symmetry with Diploblastic with no Protosomes.
• Is Acoelomates
• Platyhelminthes
• Includes Bilateral symmetry and Triploblastic characteristics.
• Contains Acoelomates and Are protostomes

Comparing and Contrasting animal phyla cont.

• Mollusca contains bilateral symmetry and triploblasticity and are coelomate woth protostomes characteristics
• Annelida bilateral symmetry that is triploblastic and contains coelomates woth protosomes
• Nematoda contains nematodes woth a bilateral symwtry where triploblasticity and proto characteristics are present Arthorpoda contains all bilateral, triploblastic,protosomes and coelomate characterisitcs
• Echinodermata contains a Bilateral symwtrythat is triploblastic with coelomates
• Deuetrostomes and a hydroskeleton

Systems

• Porifera woth Spicules and spongin Cnidaria hydrostatic Playtheyminthes hydro Mollusca shell made of calcium carbonate
• annelida hydrostatic,
• nematod hydrostatic
• Arthopoda bilateral

Reproduction

• Porifera asexuality is through fragmentation Cnidaria: external asexually through fragmentation and budding Platyhelminthes: sexual mollusas have both sexualities annelids. sexual is external where asexual is fragmentation

Chodata

• Contain a: Notochord, Dorsal Hollow nerve cord, Pharyngeal clefts, Muscular post- anal tail Bilateral with Deutorostomes
• Tunicare seaquirts deeper branching with suspension feeders
• Cephalo suspension for mobile fishy appearances.