Biodiversity Exam 4 (Part of Final Exam)

*i million species, about 35 phyla: Many species yet to describe.

*Multicellular heterotrophs: Ingest food.

*Mostly diploid (2n): Polyploid (ex. 4n); Haploid (n).

*Sexual and asexual reproduction.

*Similar ribosome structures.

*Intercellular connections.

*No cell wall.

*Extracellular Matrix (ECM) molecules: Acellular membrane that forms boundaries; Collagen, other proteins and polysaccharides.

*Development: Zygote--->Multicellular animal.

*Hox genes: Protein act as transcription factors; Assign identity to body regions; Differentiation along anterior-posterior axis.

*Diplomonads, Parabasalids, Euglenoids, Kinetoplastids, Ciliates, Dinoflagellates, Apicomplexans, Oomycetes, Diatoms, Brown algae, Red algae, Chlorophyta, Other Green algae, Plants, Fungi, Animals, Choanoflagellates.

*See book!

Precambrian origin
*Possible sponge (665 mya)
*Edicaran fauna (around 610 mya)
*Cambrian Explosion (around 540 mya): Most animal lineages present.

*Sister group to choanoflagellates: Colonial protist.

*Move to multicellularity: Specialization vs. Independence.

*Cleavage: Initial cell division; Influenced by yolk; Spiral and radial cleavage patterns.
Radial cleavage = Deuterostomes
Spiral cleavage = Protostomes

*Gastrulation: Blastula to Gastula; Ball of cells (cup-shaped structure); Origin of mouth/anus determined; Protostome/Deuterostome split.

*Formation of tissue layers.

*Orientation of body regulated by Hox genes.

*Origin of complex organs.

Origin of tissue and organ systems
*Aggregate of specialized cells

*Diploblastic (Endoderm and Ectoderm): Incomplete gut.
Ex) Cnidarians

*Triploblastic (Endoderm, Ectoderm, and Mesoderm): Complex tissues and organ systems; Presence of body cavity (coelom).

Skeletal systems

*Types of body symmetry: Asymmetry (ex. Porifera); Radial Symmetry (ex. Cnidaria); Bilateral Symmetry (ex. Hexapoda).

*Bilateral symmetry associated with cephalization and active locomotion.

*Triploblastic animals.

*Acoelomate: No body cavity.

*Pseudocoelomate: Mesoderm lines cavity; Mesoderm does not surround gut.

*Coelomate: Mesoderm lines cavity and surrounds internal organs.

*Glass sponges, Demosponges, Calcareous sponges, Placozoans, Ctenophores, Cnidarians, Arrow worms, Lophotrochozoans, Ecdysozoans, Echinodermata, Hemichordates, Chordates.

*see book

*9,000 species.

*Three lineages of sponges: Nature of skeletal support; Spicules (Silica, CaCO₃); Protein fibers.

*Specialized cells work cooperatively: Choanocytes resemble choanoflagellates.

*Porous body adapted for filter feeding: Ostia, Osculum, Spongocoel.

*Around 11,000 species.

*Diplobastic animals (2 tissue layers) with radial symmetry.

*Incomplete gut.

*Nematocysts born on tentacles: Prey capture and defense; Hooks, barbs, toxins.

*Polyp (sessile, stationary, attached) and Medusa (pelagic, swimming, open water) forms

*Polyp form most conspicuous/common.

*Solitary<---------->Colonial.

*Specialization of individuals.

*Sexual and asexual reproduction.

*Medusa form most conspicuous/common.

*Abundant mesoglea between tissue layers.

*Active predators.

*Very toxic (some species): Cardiotoxic, Neurotoxic, Hemotoxic, Dermatonecrotic (skin toxic).

*Great vision.

*Medusa stage absent.

*Radial septa.

*Anemones, Hard corals, Soft corals.

*Symbiotic algae common: Dinoflagellates; Mutualism (Nutrients [N,P], Access to light [live in shallow water], Carbohydrates, Oxygen); Significance for CaCO₃ precipitation.

*Coral reef ecosystems: Reefs through time, Current diversity and production.