Review - Can you name and give an example of each invertebrate phyla? Ancestral protists

Porifera Platyhelminthes Mollusca Arthropoda Chordata Cnidaria Nematoda Annelida Echinodermata Pseudocoelom PROTOSTOMES Coelom from cell masses DEUTEROSTOMES Coelom from digestive tube Review - Can you complete the missing invertebrate evolutionary features? Bilateral symmetry No true tissues Ancestral protists

Chordates The proper name for vertebrates is chordates. All chordates share three features at some stage in their life: Dorsal nerve cord – a main nerve for the body from which other nerves branch off Notochord – a rod of cartilage along the back of the body, often found only in the embryo Gill slits – in the pharnyx or throat. In terrestrial animals this is only seen in the embyro.

Chordates

In human embryos the part that develops into gills in fish become pharyngeal arches. The first arch becomes the jawbone, others parts of the ear and head.

Invertebrate Chordates !! There are two unusual groups in the chordate family, tunicates (sea squirts) and lancelets. They have no head and lack a brain but they do have all 3 features of chordates. Head NOTOCHORD DORSAL, HOLLOW NERVE CORD Mouth Pharynx PHARYNGEAL SLITS Digestive tract Water exit Anus POST- ANAL TAIL

Vertebrate Chordates The vertebrates are divided into two groups: Agnathans or jawless fish which are the oldest chordates in the oceans. Examples include lampreys and hagfish.

Vertebrate Chordates Gnathostomata or jawed animals. The jaw is an evolutionary trait that increased the range of food choices. Jawed fish are divided into: the ancient cartilaginous fish like sharks and rays The bony fish like salmon Jaw bones evolved by the modification of skeletal supports of the gill slits.

Evolution of marine chordate animals. E Fish phylogeny

Evolution of land chordate animals.

Land Chordates On land the four phyla of vertebrates are: Amphibians – cold blooded animals, adults have 4 limbs, start life in water, adults live on land Reptiles – cold blooded animals, have developed an amnion or sac to protect the eggs laid on land Birds – warm blooded animals that have developed a beak, and feathers for flying Mammals – warm blooded animals, have hair and feed their young milk from mammary glands. Some mammals have moved from land back into water like seals, otters, dolphins and whales. Homework – Read p 504 – 508 Complete the worksheet