Conservation and Ecology of Marine Reptiles

MARE 494Dr. Turner

Summer 2007

Body PlanDermochelyids – streamlined body, tapers at shouldersLong clawless fore limbs5 dorsal ridges run length of carapace

Cheloniids – shells composed of bone overlaid by keratinous scutesMargins of scutes don’t align with bony suturesShell reduced compared with other turtles

Scutes & ScalesScutes – keratinous plates found on the shell

Scales – thickened areas of epidermis & keratin that cover the skin & head

Provide taxonomic information & act as landmarks for describing body location

Scutes & ScalesCarapace – dorsal surface of the shell

Plastron – ventral surface of the shell

Scutes & ScalesDermocheyids – possess small scales on throat & shell as hatchlings – are shedNo scutes

Cheloniids – keratinaceous scutes covering skeletal shellNumber & arrangement are species-specific

Designated by position & number

Scutes & Scales

Scutes & Scales

Scutes & Scales

Scutes & ScalesDermocheyids – characterized by a leathery shell covering a mosaic of thin body platesDeep to the body plates is a layer of dense fibrous tissue & fat

Cheloniids – bony shell with distinctive scutes – form similar among speciesNo blubber layer

Carapace

Carapace

Heads & BeaksDermocheyids – covered with smooth skin hatchlings – small scales on face & throat

Cheloniids – large scales covering dorsal and lateral headNeck & throat covered in moderately keratinized skin

Heads & Beaks

Heads & Beaks

Heads & BeaksRhamphotheci – keratinous beaks of the upper & lower jaws in cheloniids

Form differs with diet and can be used to identify species

Dermochelyids – lack a distinctive rhamphotheca on either jawSkin of jaws more heavily keratinized than other pasts of the body

Heads & Beaks

Skeletal AnatomyForelimbs of all species are elongated as wing-like flippers

Exhibit hyperphalangy – lengthening of the phalanges; shortening, flattening, & fusing of the radius & ulna

Hindlimbs – less elongated and more paddle-like in form

Appendicular SkeletonClaws – same on fore & hindlimbs

Chelonia & adult Natator – 1 claw on each foot

Remaining Cheloniids – 2 claws on each foot

Skeletal AnatomyForelimbs - of all species are elongated as wing-like flippers - humerous, radius, ulna, carpals, metacarpals, phalanges - functionally fused by connective tissue

Hindlimbs – less elongated and more paddle-like in form - flattened to rudder-like structure

Skeletal AnatomyExhibit hyperphalangy – lengthening of the phalanges; shortening, flattening, & fusing of the radius & ulna

Similar in other marine adapted species?

Appendicular Skeleton

Appendicular Skeleton

The SkullSkull shape plus the form & patterns of bones on the roof of the mouth are diagnostic for species identification

The SkullSkull shape plus the form & patterns of bones on the roof of the mouth are diagnostic for species identification

The SkullLeatherback – wide posterior, rounded anteriorly; large orbits, no parietal notches - loosely articulated bones

Cheloniid – partial secondary palate - tightly articulated bones

LoggerheadKemp’s Ridley Olive Ridley

Green Hawksbill Leatherback

The Skull

The SkullGreen – rounded, short snout, shallow parietal notch

Loggerhead, Ridleys & Flatback – large, wide posteriorly, tapers anteriorly to orbits, wide parietal notches

Hawksbill – long & narrow (L 2x W), snout tapers to point, deep parietal notches

Head & Neck Musculature

Head & Neck MusculatureMuscle actions in marine turtles:Flexion – bending parts of a jointExtension – straightening of those parts

Protraction – moving outward & forwardRetraction – moving inward & backward

Head & Neck MusculatureMuscle actions in marine turtles:Abduction – moving away from plastronAdduction – moving toward plastron

Rotation – turns about its axis

Depression – opens the jaws (abduction)Elevation – closes the jaws (adduction)

Brains!Central nervous system

Brain – fore, mid, hind

Forebrain – posterior cerebrum

Midbrain – eye to posterior aspect of optic lobe

Hindbrain – ear to posterior cerebellum

Brains!

Cerebrum- region of the brain that regulates language & communication, movement, olfaction, memory, and emotion

Cerebellum – region of the brain that plays an important role in the integration of sensory perception and motor output

“There’s something wrong with his medulla oblongata...” - Colonel Sanders

Brains!

Medulla oblongata – region of the brain to control autonomic functions (breathing & heartbeat), relay nerve messages, processing of inter-aural time differences for sound localization

Olfactory bulb – very old part of the brain; processes smell

Optic lobe - part of the brain where vision is processed; the optic nerves partially cross

“Well, folks, Mama's wrong again.” - Colonel Sanders

Brains!

Brains!

Specific landmarks identifying locations of the parts of the brain differ slightly among Cheloniids; greatly from Dermochelys

- leatherback brain housed deeply; pineal organ extends dorsally in cartilaginous cone

- used for light detection

“To enter, send me your parents' brains. Or write "Parents‘ brains" on a three by five card, and send it to... – Zombie Krusty

Brains!“Braaaaains... Use your brains to help us! Your delicious braaaains...” –Homer Simpson