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
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
•Oldest fossil record from 150 million years ago
•Camouflage on sea floor
Rays
•
Plate-like teeth
•
•
Skates
•
Bear live young
(viviparous)
Small teeth
•
Egg laying (oviparous)
Stinging spine
•
Dorsal fin
•
No stinging spine
Shark
Skin covered with denticles, which are small razorsharp 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