LIFE 103 Animal Diversity Ch 27

Opisthokonta

Phylum that contains animals, fungi, and choanoflagellates

Animals (Metazoa)

Eukaryotic, multicellular, heterotrophic, mobile, do not have a cell wall and reproduce sexually.

Porifera

First branch from the common ancestor. Basal clade. No true tissues or symmetry. Has a sessile stage as an adult (no movement) but a swimming stage as a larva.

Sponge water movement

Water moves through by flagellate choanocytes. Water moves through the ostia and exits via the big hole at the top (osculum).

Endocytosis

Intracellular digestion, very small food particles because its needs to be able to be digested by the individual cells. (Amoebocytes)

Bilateral

Has the same mirror image on the right and left. Most animals are bilateral and triploblastic.

Radial

Can be cut into pie pieces and be symmetrical. Includes Cnidarians and ctenophores.

True tissues

Cells are arranged in organized, connected groups that work together to form tasks.

Cephalization

Sensory organs are mainly towards the front of the animal, forming a brain, nerves, nerve cord, and usually a skull.

Diploblastic

2 layers of cells: endoderm and ectoderm. Animals only have a 1-orifice, incomplete digestive tract.

Endoderm

Gut lining

Ectoderm

Outer covering

Ctenophora

Comb jellies, diploblastic and bioluminescent.

Sea walnut

Feed on zooplankton. Preyed upon by turtles, fish, and jellies. Highly invasive.

Blastula

Formation of embryo (a hollow ball)- mass of dividing cells.

Gastrulation

Digestive system formation

Protostomes

The mouth forms first during gastrulation. The second hole to form is the anus. (Lophotrochozoan) (Ectozoan)

Deuterostomes

Anus forms first, 2nd hole is the mouth. (Echinodermata) (Chordata)

Triploblastic

Have 3 tissue layers, ecto, meso, and endoderm. Ecto now also includes the nervous system. Mesoderm is muscle, and endoderm is still digestive.

Closed Circulatory system

System where blood stays enclosed in vessels.

Open circulatory system

Blood is pumped freely through the body cavity and diffuses back into the heart and/or other organs.

No circulatory system

Some animals do not have a circulatory system and rely on diffusion of gases through the skin.

Ecdysis

Some animals molt to grow larger. (Exoskeleton)

Cnidarians

Includes jellyfish, corals, hydrozoans, and sea anemones. Has two body forms: Medusa and polyp. Invertebrates, diploblastic, and radially symmetrical.

Medusa

Mobile, mouth is usually faced downward. (Jellyfish)

Polyp body form

Sessile (doesn’t move). Usually attached to something, mouth up. (Coral, sea anemones, and hydrozoans.)

Cnidarian feeding

Extracellular digestion. Releases enzymes to digest prey in the gastrovascular cavity and absorb nutrients. (Allows them to eat larger prey.)

Nematocytes

All cnidarians have this, a trigger cell for nematocysts.

Nematocysts

Organ, modified vacuole that shoots barbed venom string.

Berghia

Eat anemones and can hold onto nematocysts and protect themselves with them.

Stony corals

Important reef builders. Deposit calcium carbonate cups for each polyp.

Dinoflagellets

Do photosynthesis and often live in symbiosis with corals and other cnidarians. Provide most primary production in shallow-water reefs but can disappear and lead to bleaching.

Arthropods

Have chitinous exoskeleton that covers segmented body with paired jointed appendages. Have an open circulatory system, cephalization, and either compound or ocelli eyes. 4 groups: Chelicerata, myriapods, crustaceans, and hexapods.

Chelicerata

Include spiders, scorpions, mites, and horseshoe crabs. Have chelicerae mouth parts (fangs or claws). Have a cephalothorax and abdomen. 4 pairs of legs and no antennae.

Cephalothorax

Anterior parts: 6 pairs of appendages, 2 chelicerae, and 4 pairs of walking legs.

Abdomen

Posterior, include reproductive organs.

Myriapods

Centipedes (1 pair of walking legs per body segment, carnivorous) and millipedes (2 pairs per segment, herbivores) have antennae and uniramous appendages. Least diverse.

Crustacea

Have a head, thorax, and abdomen with jointed appendages on segments. Non-insect crustaceans are aquatic (crabs and shrimps). Have biramous appendages (two branches). 2 pairs of antennae, 3 pairs of chewing appendages. Have gas exchange through gills or across cuticle.

Nauplius

Several larval stages, in class crustacea.

Hexapoda

Six-legged, also uniramous. Have soft bodies and lack an external mouthpart →mandibles. Have a tracheal system, antennae, thorax, and abdomen. Most diverse and abundant. Insects.

Tagma

Group of segments fused for function, ex: cephalothorax and abdomen.