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

CHONDRICHTHYESBrenna 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

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

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

Rays

• Plate-like teeth

• Bear live young (viviparous)

• Stinging spine

Skates

• Small teeth

• Egg laying (oviparous)

• Dorsal fin

• No stinging spine

•Oldest fossil record from 150 million years ago•Camouflage on sea floor

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.

sourceshttp://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