Animal and Eukaryotic Diversity Study Notes

Major Eukaryotic Groups:
- Brown algae
- Diatoms
- Water molds
- Apicomplexans
- Dinoflagellates
- Ciliates
- Chlorarachniophytes
- Foraminiferans
- Land plants
- Green algae
- Red algae
- Glaucophyte algae
- Kinetoplastids
- Euglenids
- Diplomonads
- Parabasalids
- Animals
- Choanoflagellates
- Fungi
- Plasmodial slime molds
- Cellular slime molds
- Lobose amoebae
Classification of Eukaryotes:
- All eukaryotes are protists except for fungi, animals, and land plants.
- Major Supergroups:
- Unikonta
  - Amoebozoa
  - Opisthokonta
- Bikonita
  - Excavata
  - Plantae
  - Rhizaria
  - Alveolata
  - Stramenopila
Multicellularity:
- Evolved independently at least seven times.

Overview of Animal Taxonomy:
- Monophyletic Group: All animals share a common ancestor.
- Classification of major animal phyla based on developmental patterns, symmetry, and body plans.
- Basic Structure:
- Multicellularity
- Various levels of tissue organization

Non-Bilaterians:
- Placozoa: 1 species
- Ctenophora: 190 species
- Acoela: 350 species
- Porifera (Sponges): 8500 species
- Cnidaria: 11,500 species
Bilaterians: Divided into two major groups:
- Protostomes:
- Lophotrochozoa: e.g., Mollusca, Annelida (Segmented worms)
- Ecdysozoa: e.g., Arthropoda, Nematoda
- Deuterostomes:
- Echinodermata (like sea stars)
- Chordata (including vertebrates)

All animals are believed to have arisen from a single multicellular ancestor.
Sponges as the Most Ancient Lineage:
- Fossil evidence supports that sponges are among the earliest animals.

Both sponges and choanoflagellates share several characteristics:
- Both are benthic and sessile organisms.
- Feeding occurs via choanocytes in sponges and similar cells in choanoflagellates.

Characteristics Typical to Animals:
- Multicellularity
- Extracellular matrix
- Introduction of tissues and organs from embryonic germ layers.
- Distinct reproductive strategies (e.g., eggs and sperm).

Group Overview:
- Radially symmetric, diploblastic body structure.
- Cells called cnidocytes, which have stinging structures called nematocysts.
- Includes classes like Hydrozoa, Scyphozoa, Cubozoa, and Anthozoa.
Hydrozoa:
- Marine group; includes species with both polyp and medusa stages.
Scyphozoa:
- Marine jellies; exhibit reduced polyp stage.
Cubozoa:
- Box-shaped medusae; many are poisonous.
Anthozoa:
- Assumes no medusa stage; includes corals and sea anemones.
- Reef-building corals often have symbiotic algae.

Sponges previously considered colonies of protists due to their ability to reaggregate after dissociation.
Essential evidence for classification includes the presence of flagellated feeding cells and their unique feeding mechanisms.

Synapomorphies for Animals:
- Multicellularity, extracellular matrix, nerve cells
- Comparison of feeding structures in sponges and choanoflagellates provides insight into the evolutionary history of animals.