| Crocodilian
and Turtle Study Guide |
Remember that you should be able to identify specimens to
family by external morphological characteristics alone. Do not rely
upon coloration characteristics since these are often bleached out in preserved
specimens. Typical coloration patterns also tend to vary greatly in
nature. The following information was presented in lab at each station.
Crocodilians
Turtles
Connecticut turtles
Families of Crocodilians
Alligatoridae
Crocodylidae
Gavialidae
Alligatoridae
- alligators and caimans
- snout not set off sharply from posterior point of skull
- snout not more than 3.5 times as long as the width of the base of the skull
- fourth tooth of lower jaw fits into pocket in upper jaw, not visible when mouth closed
Specimens on display:
Alligator mississippiensis
Caiman crocodilus
Crocodylidae
- snouts of variable shape, narrow and tapered in Crocodilus acutus
- snouts not set off sharply from posterior part of skull
- fourth tooth of lower jaw visible outside of mouth when mouth closed
Specimens on display:
Crocodilus acutus
Gavialidae
No specimens available
Turtle Families
Pleurodira
Pelomedusidae
Podocnemidae
Chelidae
Cryptodira
Dermochelidae
Cheloniidae
Chelydridae
Kinosternidae
Dermatemydidae
Trionychidae
Carettochelidae
Bataguridae
Emydidae
Testudinidae
Pelomedusidae
- African pond and box turtles
- aquatic and semiaquatic morphologies
Specimens on display:
Pelomedusa subrufra
Podocnemidae
- South American river turtles
Specimens on display:
Podocnemis sp.
Chelidae
No specimens available
Dermochelidae
- leatherback turtle
- highly modified leathery shell
- several distinct longitudinal ridges on shell
- limbs proportionally longer than in other sea turtles
- limbs modified into flippers, no claws
Specimens on display:
Dermochelys coriacea
Cheloniidae
- marine turtles
- all limbs modified into flattened flippers for swimming, claws present
- large size compared to most terrestrial species
- shell bony with horny shields
Specimens on display:
Caretta caretta
Chelonia mydas
Chelydridae
- snapping turtles
- rough carapace, often with distinct ridges
- plastron small and cross-shaped
- plastron has 9 shields joined to the carapace by cartilage
- rear margin of shell strongly serrate, bridge shorter than broad
Specimens on display:
Chelydra serpentina
Macrochelys temmickii
Kinosternidae
- mud and musk turtles
- carapace generally smooth and elongate
- Sternotherus lacks obvious hinge on plastron, Kinosternon has hinges on plastron
- plastron has 11 or fewer shields
- rear margin of shell nearly smooth, bridge at least as long as broad
Specimens on display:
Kinosternon bauri
Kinosternon leucostomum
Kinosternon subrubrum
Sternotherus carinatus
Sternotherus minor
Sternotherus odoratus
Dermatemydidae
No specimens available
Trionychidae
- softshell turtles
- flat, soft shells lacking bony armor
- long necks with elongate skulls
- snorkel-like snouts
- claws 3-3 (front- back)
Specimens on display:
Apalone ferox
Apalone spinifera
Carettochelidae
No specimens available
Bataguridae
No specimens available
Emydidae
- most species aquatic or semi-aquatic pond turtles
- most have oval, streamlined shells
- plastron has 12 shields
- males of Chrysemys, Pseudemys, Trachemys, and Graptemys have elongated claws on forefeet
- Terrepene is terrestrial box turtles, with high domed shells and hinged plastrons
Specimens on display:
Chrysemys picta
Clemmys guttata
Deirochelys reticularia
Emys blandingii
Glyptemys (Clemmys) insculpta
Glyptemys (Clemmys) muhlenbergii
Graptemys geographica
Graptemys kohni
Malaclemys terrapin
Pseudemys floridana
Terrapene ornata
Trachemys scripta
Testudinidae
- tortoises
- high-domed shells
- carapace joined to plastron with firm bony bridges
- plastron has 12 shields
- feet elephant-like, lack webbing
- forelimbs often covered with large, hard scales
Specimens on display:
Geochelone elegans
Geochelone impressa
Geochelone pardalis
Gopherus polyphemus
Homopus areolatus
Kinixys homeana
Testudo graeca
Connecticut Turtles
Chelydra serpentina
Sternotherus odoratus
Chrysemys picta
Clemmys guttata
Glyptemys insculpta
Glyptemys muhlenbergii
Terrepene carolina
Malaclemys terrapin
Chelydra serpentina (common snapping turtle)
Family Chelydridae
Morphological characteristics:
- shell broadly oval and moderately deep
- plastron small and cruciform
- large head with powerful jaws
- carapace with three rough keels
- long tail that is saw-toothed along upper side
- young have three well defined longitudinal keels on carapace, less distinct in adults
Living specimens:
- often covered with algae
- carapace varies from almost black to light brown
Sternotherus odoratus (common musk turtle, stinkpot)
Family Kinosternidae
Morphological characteristics:
- carapace moderately elongate and narrow, usually highly arched
- carapace keeled or smooth
- plastron small and somewhat cruciform
- plastron hinge situated between 2nd and 3rd pairs of scutes, usually not apparent to eye
- pectoral scutes squarish
- 23 marginal scutes (most other turtles have 25)
- young have prominent middorsal keel bordered by two smaller keels, tend to vanish with age
- barbels on chin and throat
- tail short
Living specimens:
- carapace dark brown to black, often covered with algae
- head dark with pair of yellow or white lines running from snout along sides of head
Chrysemys picta (painted turtle)
Family Emydidae
Morphological characteristics:
- carapace low, broad, and smoothly arched
- plastron lacks hinge
- males have longer claws than females
- axillaries and inguinals well developed
- carapacial scutes smooth
- posterior margin of carapace not serrated
- large scutes of carapace in straight rows across back
Living specimens:
- carapace olive to dark brown, with patterns of red and yellow
- marginals always marked with red
- plastron yellow, sometimes marked with reddish brown or black
- skin dark with red and yellow markings, especially around head and neck
Clemmys guttata (spotted turtle)
Family Emydidae
Morphological characteristics:
- carapace low and smooth
- no hinge on plastron
- axillaries and inguinals rudimentary
Living specimens:
- carapace color brown or almost black, distinct yellow or orange spots
- orange spots on head
Glyptemys (Clemmys) insculpta (wood turtle)
Family Emydidae
Morphological characteristics:
- carapace roughened with concentric pyramidal grooves and ridges on each plate
- carapace low and broad
- plastron firmly attached to carapace without hinge
- axillaries and inguinals rudimentary
Living specimens:
- carapace gray or brown
- plastron yellow
- skin of head and legs salmon red or orange
- no blotch on temple
- large scutes of carapace may have yellow or red centers
Glyptemys (Clemmys) muhlenbergii (bog turtle)
Family Emydidae
Morphological characterstics:
- smallest Connecticut turtle
- plastron firmly connected to carapace, lacking hinge
- axillaries and inguinals rudimentary
- no prominent growth rings on dorsal scutes
Living specimens:
- carapace dark brown to black with yellow or red markings
- head black with distinctive orange or yellow spot on each side
Terrepene carolina (eastern box turtle)
Family Emydidae
Morphological characteristics:
- carapace high and domed
- plastron large and connected to carapace by cartilage
- two lobes of plastron connected by hinge
- plastron of males concave
- front of upper jaw with hooked beak
- four toes on each hind foot
Living specimens:
- color highly variable, usually striking yellow or orange mottling on dark background
- head and legs marked with orange and yellow
- eyes of males bright red, females have brown eyes
Malaclemys terrapin (diamondback terrapin)
Family Emydidae
Morphological characteristics:
- carapace flattened with distinct keel
- carapace wedge-shaped when viewed from above, widest at rear
- each large shield/scute deeply marked with concentric rings
- plastron oblong with nearly parallel sides
- axillaries and inguinals well developed
Living specimens:
- carapace usually brown or gray
- plastron orange, gold, or olive
- head usually light gray and marked with distinct black spots, limbs spotted
Crocodilians
Turtles
Connecticut turtles
Families of Crocodilians
Alligatoridae
Crocodylidae
Gavialidae
Alligatoridae
- alligators and caimans
- snout not set off sharply from posterior point of skull
- snout not more than 3.5 times as long as the width of the base of the skull
- fourth tooth of lower jaw fits into pocket in upper jaw, not visible when mouth closed
Specimens on display:
Alligator mississippiensis
Caiman crocodilus
Crocodylidae
- snouts of variable shape, narrow and tapered in Crocodilus acutus
- snouts not set off sharply from posterior part of skull
- fourth tooth of lower jaw visible outside of mouth when mouth closed
Specimens on display:
Crocodilus acutus
Gavialidae
No specimens available
Turtle Families
Pleurodira
Pelomedusidae
Podocnemidae
Chelidae
Cryptodira
Dermochelidae
Cheloniidae
Chelydridae
Kinosternidae
Dermatemydidae
Trionychidae
Carettochelidae
Bataguridae
Emydidae
Testudinidae
Pelomedusidae
- African pond and box turtles
- aquatic and semiaquatic morphologies
Specimens on display:
Pelomedusa subrufra
Podocnemidae
- South American river turtles
Specimens on display:
Podocnemis sp.
Chelidae
No specimens available
Dermochelidae
- leatherback turtle
- highly modified leathery shell
- several distinct longitudinal ridges on shell
- limbs proportionally longer than in other sea turtles
- limbs modified into flippers, no claws
Specimens on display:
Dermochelys coriacea
Cheloniidae
- marine turtles
- all limbs modified into flattened flippers for swimming, claws present
- large size compared to most terrestrial species
- shell bony with horny shields
Specimens on display:
Caretta caretta
Chelonia mydas
Chelydridae
- snapping turtles
- rough carapace, often with distinct ridges
- plastron small and cross-shaped
- plastron has 9 shields joined to the carapace by cartilage
- rear margin of shell strongly serrate, bridge shorter than broad
Specimens on display:
Chelydra serpentina
Macrochelys temmickii
Kinosternidae
- mud and musk turtles
- carapace generally smooth and elongate
- Sternotherus lacks obvious hinge on plastron, Kinosternon has hinges on plastron
- plastron has 11 or fewer shields
- rear margin of shell nearly smooth, bridge at least as long as broad
Specimens on display:
Kinosternon bauri
Kinosternon leucostomum
Kinosternon subrubrum
Sternotherus carinatus
Sternotherus minor
Sternotherus odoratus
Dermatemydidae
No specimens available
Trionychidae
- softshell turtles
- flat, soft shells lacking bony armor
- long necks with elongate skulls
- snorkel-like snouts
- claws 3-3 (front- back)
Specimens on display:
Apalone ferox
Apalone spinifera
Carettochelidae
No specimens available
Bataguridae
No specimens available
Emydidae
- most species aquatic or semi-aquatic pond turtles
- most have oval, streamlined shells
- plastron has 12 shields
- males of Chrysemys, Pseudemys, Trachemys, and Graptemys have elongated claws on forefeet
- Terrepene is terrestrial box turtles, with high domed shells and hinged plastrons
Specimens on display:
Chrysemys picta
Clemmys guttata
Deirochelys reticularia
Emys blandingii
Glyptemys (Clemmys) insculpta
Glyptemys (Clemmys) muhlenbergii
Graptemys geographica
Graptemys kohni
Malaclemys terrapin
Pseudemys floridana
Terrapene ornata
Trachemys scripta
Testudinidae
- tortoises
- high-domed shells
- carapace joined to plastron with firm bony bridges
- plastron has 12 shields
- feet elephant-like, lack webbing
- forelimbs often covered with large, hard scales
Specimens on display:
Geochelone elegans
Geochelone impressa
Geochelone pardalis
Gopherus polyphemus
Homopus areolatus
Kinixys homeana
Testudo graeca
Connecticut Turtles
Chelydra serpentina
Sternotherus odoratus
Chrysemys picta
Clemmys guttata
Glyptemys insculpta
Glyptemys muhlenbergii
Terrepene carolina
Malaclemys terrapin
Chelydra serpentina (common snapping turtle)
Family Chelydridae
Morphological characteristics:
- shell broadly oval and moderately deep
- plastron small and cruciform
- large head with powerful jaws
- carapace with three rough keels
- long tail that is saw-toothed along upper side
- young have three well defined longitudinal keels on carapace, less distinct in adults
Living specimens:
- often covered with algae
- carapace varies from almost black to light brown
Sternotherus odoratus (common musk turtle, stinkpot)
Family Kinosternidae
Morphological characteristics:
- carapace moderately elongate and narrow, usually highly arched
- carapace keeled or smooth
- plastron small and somewhat cruciform
- plastron hinge situated between 2nd and 3rd pairs of scutes, usually not apparent to eye
- pectoral scutes squarish
- 23 marginal scutes (most other turtles have 25)
- young have prominent middorsal keel bordered by two smaller keels, tend to vanish with age
- barbels on chin and throat
- tail short
Living specimens:
- carapace dark brown to black, often covered with algae
- head dark with pair of yellow or white lines running from snout along sides of head
Chrysemys picta (painted turtle)
Family Emydidae
Morphological characteristics:
- carapace low, broad, and smoothly arched
- plastron lacks hinge
- males have longer claws than females
- axillaries and inguinals well developed
- carapacial scutes smooth
- posterior margin of carapace not serrated
- large scutes of carapace in straight rows across back
Living specimens:
- carapace olive to dark brown, with patterns of red and yellow
- marginals always marked with red
- plastron yellow, sometimes marked with reddish brown or black
- skin dark with red and yellow markings, especially around head and neck
Clemmys guttata (spotted turtle)
Family Emydidae
Morphological characteristics:
- carapace low and smooth
- no hinge on plastron
- axillaries and inguinals rudimentary
Living specimens:
- carapace color brown or almost black, distinct yellow or orange spots
- orange spots on head
Glyptemys (Clemmys) insculpta (wood turtle)
Family Emydidae
Morphological characteristics:
- carapace roughened with concentric pyramidal grooves and ridges on each plate
- carapace low and broad
- plastron firmly attached to carapace without hinge
- axillaries and inguinals rudimentary
Living specimens:
- carapace gray or brown
- plastron yellow
- skin of head and legs salmon red or orange
- no blotch on temple
- large scutes of carapace may have yellow or red centers
Glyptemys (Clemmys) muhlenbergii (bog turtle)
Family Emydidae
Morphological characterstics:
- smallest Connecticut turtle
- plastron firmly connected to carapace, lacking hinge
- axillaries and inguinals rudimentary
- no prominent growth rings on dorsal scutes
Living specimens:
- carapace dark brown to black with yellow or red markings
- head black with distinctive orange or yellow spot on each side
Terrepene carolina (eastern box turtle)
Family Emydidae
Morphological characteristics:
- carapace high and domed
- plastron large and connected to carapace by cartilage
- two lobes of plastron connected by hinge
- plastron of males concave
- front of upper jaw with hooked beak
- four toes on each hind foot
Living specimens:
- color highly variable, usually striking yellow or orange mottling on dark background
- head and legs marked with orange and yellow
- eyes of males bright red, females have brown eyes
Malaclemys terrapin (diamondback terrapin)
Family Emydidae
Morphological characteristics:
- carapace flattened with distinct keel
- carapace wedge-shaped when viewed from above, widest at rear
- each large shield/scute deeply marked with concentric rings
- plastron oblong with nearly parallel sides
- axillaries and inguinals well developed
Living specimens:
- carapace usually brown or gray
- plastron orange, gold, or olive
- head usually light gray and marked with distinct black spots, limbs spotted
