Animal Diversity - Lecture 2

The 4 Supergroups of Eukarya

1. Excavata

2. SAR

3. Archaeplastida

4. Unikonda

Type of Eukaryotes in Excavata

Just protists

Type of Eukaryotes in SAR (stramenopiles, alveolates, rhizarians)

Just protists

Type of Eukaryotes in Archeaplastida

Protists and plants

Type of Eukaryotes in Unikonda

Protists, Fungi, and Animals

2 Clades of Unikonda

1. Amoebozoans

2. Opisthokont (Choanoflagellates)

   (I pissed the conch)

How protists differ from the other eukaryotic organisms

They are unicellular, unlike the other three

The Ten Major Phyla

Porifera, Cnidaria, Chordata, Echinodermata, Mollusca, Platyhelminthes, Brachiopoda, Annelida, Nematoda, Athropodes

Example of Porifera

Sponge

Example of Cnidaria

Coral, Jellies

Example of Chordata

Vertebrates, HUMANS!

Example of Echinodermata

Anything spiky! Sea Urchins

Example of Mollusca

Octopus! Scallops!

Example of Platyhelminthes

Flatworms

Example of Brachiopoda

Clam-like organisms, snails, and chitins

Example of Annelida

Leeches

Example of Nematoda

Earthworms

Example of Arthropodes + What makes them Special!

Insects, crabs, and spiders

• Special because they are the most diverse group!

5 Animal Characteristics

1. Interconnected multicellular (gap and tight junctions)

2. No cell walls

3. Can move (they gta go find food)

4. Heterotrophic

5. 3 Embryotic Tissue Layers (Germ Layers) [except Porifera and Cnidarians]

Animal Life Cycle

• Diplontic most of its life

• Only haplontic when gametes

Metamorphosis

Going from one stage of life to another, characterized differently by habitat/food they eat/morphology

Sister Taxon to Animals

Choanoflagellates

How Choanoflagellates are similar to Sponges

• Sponges possess choanocytes, which look very alike to individual choanoflagellates

Choanocytes

They push water into the cell, along with their nutrients, to feed the sponge

Metazoan

A monophyletic group used to group together all animals

Porifera

A group used to group up all sponges together

• the best basal taxon possible for animals because they lack tissues

Porifera Structure

Two cell layers, not tissues

• Epidermis → exterior

• Choanoderm → has the choanocytes

Middle Region

• Phorocytes

• Mesohyl

Process of Digestion: Porifera

Water is moved into the spongocoel by choanocytes, along with any nutrients. This then gets moved to the amoebocytes, which do phagocytosis to digest the nutrients and then distribute it to the body

How sponges are totipotent

All sponge cells are stem cells and can turn into whatever cell they want/need to be

2 Potential Results of putting a Sponge through a Grater

• The cells broken up will spontaneously reassemble

• The cells broken up will stay broken up and each develop like a zygote, producing way more sponge cells

Symmetry of Sponges

None because they are asymmetrical :D

In what Phylum Radical Symmetry Arose

Cnidaria

Oral vs. Aboral End

Oral end: Mouth

Aboral end: Opposite the mouth (not necessarily the anus)

Tissues

Groups of specialized cells for a certain structure/function

• Sometimes separated by membranous layers

• Character of Eumatazoans

Metazoans vs. Eumetazoans

Metazoans: all animals

Eumetazoans: “true” animals (paraphyletic group) possessing tissues like muscles and nerves [thus excluding polifera]

Polyp

One of two types of Cnidarian Body Forms with the mouth facing upward, crawling (less movement), and cylindrical shape

Medusa

One of two Cnidarian body forms with the mouth/anus facing down, tentacles moving down, and more movement

Where the name Cnidarian Comes from

All have Cnidocytes, which are “stinging cells” (Think Jellyfish)

Protostome Cleavage

Spiral and Determinate

• Shape is unique

• All 8 cells have a given role; if one leaves, the final result will lack something essential

Deuterostome Cleavage

Radical and Indeterminate

• Radical: all cells are on top of one another

• Indeterminate: cells can break off and still divide like normal zygotes (why identical twins exist)

Clade

Monophyletic Group with common ancestors

• DIVERGENT EVOLUTION

Grade

No relationship between organisms, only their anatomy is similar

• CONVERGENT EVOLUTION

Coelem

A type of body cavity in animals [which is not in earthworms lmao]

Eucoelomates: Body cavity

Mesoderm completely lines both the endoderm and the ectoderm

Pseudocoelamates: Body cavity

The mesoderm only coats one of the germ layers, not both

Acoelomates: Body cavity

There is no empty space between the endoderm and the ectoderm because the mesoderm takes it all up!