http://www.youtube.com/watch?v=NQkIyttPEoU

CHONDRICHTHYES Brenna Pettersen, Brianna McClocklin, Zarria Mackey and Lyndsey Torcolacci

Classification Kingdom – Animalia Phylum- Chordata Class – Chondrichthyes Subclasses: Elasmobranchii and holocephali

Distinguishing Characteristics Cartilage skeletons No swim bladder or lungs Ectothermic Internal fertilization Gills All carnivores * Jaws, paired appendages, deep visceral arches next to the pharynx, an inner ear containing 3 semicircular canals, a paired nasal cavity. Well developed electroreceptors.
* Cartilaginous endoskeleton. Skin covered by placoid scales and mucous glands; Teeth are modified placoid scales. teeth unattached to jaws,

Holocephali Currently 30 known species Limited to cold and salt water Found at 200 – 2000 m Closest living relative are sharks Has grinding plates instead of teeth Chimeras only surviving group Sister order 400 million years ago

Elasmobranchii Sharks, skates and rays Five to seven gill pairs Rigid dorsal fins and spines Small placoid scales Teeth are in series; upper jaw not fused to the cranium Widely distributed in tropical and temperate waters

Rays & Skates Oldest fossil record from 150 million years ago Camouflage on sea floor Rays Plate-like teeth Bear live young (viviparous) Stinging spine Skates Small teeth Egg laying (oviparous) Dorsal fin No stinging spine

Shark Skin covered with denticles, which are small razor- sharp teeth have very good senses can be viviparous, oviparous or ovoviviparous Over 400 species Oldest species in the cartilaginous taxonomy

Evolution The earliest known cartilaginous fishes were ancient sharks that were descended from bony-skeleton placoderms. Swam in oceans 420 mya, 200 mya before the first dinosaur appeared on land. 40 million years ago the two subclasses divided

Fun facts Over 17% at risk with extinction Ancient Greeks used electric rays as anaesthetic More people are killed by vending machines than sharks The largest ray is the Manta Ray which can have a 7 meter wing span.

sources http://vertebrates.voices.wooster.edu/chondrichthyes/ http://www.seawater.no/fauna/chordata/Holocephali.html ftp://ftp.fao.org/docrep/fao/009/y4160e/y4160e41.pdf http://www4.bluevalleyk12.org/bvnw/jmohn/zoology/notes/phylum_chart_3.pdf http://www.facebook.com/l.php?u=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FChondrichthyes&h=FAQHTyR7V http://www.fish.wa.gov.au/Documents/recreational_fishing/fact_sheets/fact_sheet_rays.pdf http://ocean.nationalgeographic.com/ocean/photos/ocean-rays/#/rays05-manta-ray-maldives_17861_600x450.jpg http://www.flmnh.ufl.edu/fish/education/questions/raybasics.html http://www.ucl.ac.uk/museums-static/obl4he/vertebratediversity/chondrichthyes.html http://www.nhc.ed.ac.uk/index.php?page=493.470.475 http://palaeo.gly.bris.ac.uk/palaeofiles/fossilgroups/chondrichthyes/Characters/synapomorphies.html