Scientists have created a logical system of classifying most living organisms on Earth using a system called taxonomy. Sharks fit into the system under the following organization:
- Kingdom: Animalia
- Phylum: Chordata
- Subphylum: Vertebrata
- Class: Chondrichthyes
- SubClass: Elasmobranchii (sharks and rays)
- Superorder: Euselachii
- Orders:
- Pristiophoriformes (sawsharks)
- Squantiniformes (angel sharks)
- Squaliformes (dogfish sharks)
- Chlamydoselachiformes (frilled sharks), sometimes included as part of Order Hexinforme
- Echinorhiniformes (bramble sharks), sometimes included as part of Order Squaliforme
- Hexanchiformes (cow sharks)
- Lamniformes (mackerel sharks)
- Carcharhiniformes (ground sharks)
- Orectolobiformes (carpet sharks)
- Heterodontiformes (bullhead sharks)
How did scientists come up with this classification scheme? These fishes share certain characteristics. To be classified in Class Chondrichthyes, the fish has to have a skeleton made of cartilage, not bone, have a true upper and lower jaw, and nostrils below their head. Subclass Elasmobranchii fish have multiple paired gill openings on the side of their heads. There are more specific characterizations that further define each family, genus and species within every order.
Shark taxonomy is a dynamic system, hardly agreed upon. New specimens are discovered and DNA analysis is increasingly resulting re-classifications.
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| Frilled Shark |
Bramble Shark
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Angel Shark
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Bullhead shark |
Mackerel shark |
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Cow shark |
Dogfih shark |
Saw shark
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Carpet shark |
Ground shark |
| Order |
Frilled
Shark |
Cow
Sharks
|
Bramble Sharks |
Dogfish
Sharks |
Angel
Sharks |
Saw
Sharks
|
Bullhead Sharks |
Carpet
Sharks
|
Mackerel Sharks |
Ground
Sharks
|
Chlamydo-
selachiformes |
Hexanchi-
formes |
Echinorhini-
formes
|
Squali-
formes |
Squatini-
formes
|
Pristiophori-
formes |
Heterodonti-
formes |
Orectolobi-
formes |
Lamni-
formes |
Carcharhini-
formes |
| # Species |
2 |
4 |
2 |
119 |
19 |
9 |
9 |
39 |
15 |
277 |
| Body shape |
Long, thin,
eel-like |
Rounded |
Rounded |
Rounded |
Flattened |
Slightly flattened
|
Rounded |
Many Rounded;
some flattened
|
Rounded |
Rounded |
Mouth
position |
Terminal mouth;
blunt snout |
Underneath |
Underneath |
Underneath |
Terminal mouth;
blunt snout |
Underneath
long, blade-like, toothy snout |
Underneath;
pig-like snout
|
Underneath
Short
Ends before eyes
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Underneath
extends well past eyes |
Underneath |
| Anal fin |
Yes |
Yes |
No |
No |
No |
No |
Yes |
Yes |
Yes |
Yes |
| Dorsal Fin |
1 |
1 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
| Fin spines |
No |
No |
No |
Yes |
No |
No |
Yes |
No |
No |
No |
| # Gill slits |
6 |
6 or 7 |
5 |
5 |
5 |
5 or 6
|
5 |
5 |
5 |
5 |
Repro-
duction |
ovoviviparous |
oviparous;
egg case
auger- |
some oviparous;
ovoviviparous
|
ovoviviparous
some are oviphagous
|
variable |
Unique
Qualities |
Eel-like shape;
3-cusped teeth;
frilly growth on gils
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cockscomb-
shaped bottom teeth
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thorn-like
denticles
over body
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Many bio-
luminescent
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Shape; eyes & spiracle at top of head;
fleshy barbels
|
Long snout;
long nasal barbels |
Pronounced
brow;
|
specialized nostrils:
barbels |
"lamnoid dental pattern" |
Nictating eyelids |
| Habitat |
Deep marine waters |
Deep, often cold marine
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Deep, marine
temperate to tropical |
Marine;
many bottom-
oriented
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Marine; from temperate to tropical; bottom |
Mostly marine;
temperate
to tropical
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Marine coastal;
bottom;
temperate to tropical
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Marine
Mostly tropical
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Marine; coastal to open-ocean; cold temperate to tropical
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Virtually every marine habitat, some estuaries |
| Famous Species |
Frilled Shark
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Bluntnose Six-gill Shark |
Bramble,
Prickly Shark
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Spiny Dogfish, Gulper, Lantern, Pigmy |
Pacific Angel |
Common
Sawshark |
Port Jackson,
Horn |
Whale, Nurse
Zebra, Carpet Shark |
Basking, Mako, Megamouth,
Great White, Thresher
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Catsharks, Tiger, Bull, Hammerhead Sharks |
See the Glossary of some of term used on this page. |