Testudines Exam

Testudines

What order to turtles belong to?

Cryptodira (hidden-neck) and Pleurodira (side-neck)

What are the two major turtle clades?

Method of heat retraction and jaw pulley system

Main difference between Cryptodira and Pleuorida

3%

What % of reptiles are turtles?

Carapace and Plastron

What are the two main parts of a turtle shell?

Modified ribs and vertebrae

What bones form the carapace?

Keratinous scutes

What covers the bony shell externally?

To increase shell strength

Why are scutes misaligned with bones?

Inside the rib cage

Where are the pectoral and pelvic girdles located in turtles?

Broadening of the ribs

What was the first step in turtle shell evolution?

Expanded gastralia

What structure forms the plastron?

Doming of the shell

Final step in shell evolution?

Generalist,Terrestrial, Saxicolous (Rock-Dwelling), Aquatic (Freshwater), Aquatic (Marine)

What are the ecomorphs for turtles?

All shell shapes, have well-developed claws as well as some webbing

Key traits of generalist turtles

Elephantine feet, high-domes shell, dull coloration, slow locomotion

Key traits of terrestrial turtles

Flat shells

Key traits of saxicolous turtles

Webbed feet with claws, weird shell projections, very strong jaws, “skin folding”, lower-domed carapace

Key traits of freshwater (aquatic) turtles

Sleek, hydrodynamic shape; well-developed eyes, clear, paddle-shaped flippers, large upper eyelid and no external ear openings

Key traits of aquatic (marine) turtles

Expiration: reduce volume of visceral cavity (transverse abdominus and pectoralis)

Inspiration: expand visceral cavity (abdominal oblique and serratus)

How do turtles breathe (inspiration and expiration)

Ribs are fused into the shell

Why can’t turtles use rib ventilation?

Gas exchange through the cloaca

What is cloacal respiration?

Fitzroy river turtle (Rheodytes)

What turtle is famous for extreme cloacal respiration?

1. Simultaneous forelimb movement (sea turtles)

2. Alternate movements of all limbs (all other aquatic turtles)

Two swimming modes in turtles?

Using their hind limbs as rudders

How do sea turtles steer?

The ability to drop the temperature of body tissue below freezing without the formation of ice crystals

What is supercooling?

Surviving actual freezing using protective proteins

What is “freeze tolerance?”

Nocturnal basking

Type of basking that occurs when water temperatures are higher than optimal and air temperatures are cooler

Lacrimal salt glands that excrete Na+ and Cl-

How do sea turtles deal with drinking sea water?

No, they have keratinous beaks

Do turtles have teeth?

Suction feeding, High speed jaw closure, and Tongue luring

What are the ways that turtles eat?

Adults

What life stage has the highest survival?

10-20+ years

How long does it take turtles to reach sexual maturity?

All turtles are oviparous

Are turtles oviparous or viviparous?

Internal

What type of fertilization do turtles have?

Single median penis

What reproductive structures do males have?

Males have concave plastrons; females can have extra hinges to facilitate laying eggs; tail length is often different

What kinds of sexual dimorphism are there in turtles?

Correlation between coloration brightness and immune response

What does brightness indicate from a turtle’s shell?

Navigation & Orientation

What do turtles utilize to find their original nest?

Females

Turtles with TSD at very high temps will produce what sex:

Females

In aquatic turtles, which sex is usually larger?

Males

In tortoises, which sex is often larger?

Visual, tactile, chemical (possible vocal)

What types of communication do turtles utilize?

Galapagos tortoises (saddleback vs domed)

What are the two types of shell variation due to predation release?