Friday, January 31, 2014

Lab #2: Testudines (Nick Spies and Alex Murray)

Lab #2: Testudines
There are currently 327 identified extant species of Testudines, placed into 14 families.  In this specific lab, 8 of these extant Testudines families were examined and described.  The eight specific Testudine families that were examined in this lab are as follows:
  1. Podocnemidae (Madagascan Big-Headed Turtles & American Side-Neck Turtles)
  2. Chelidae (Australoamerican Side-Neck Turtles)
  3. Trionychidae (Soft-Shell Turtles)
  4. Cheloniidae (Hard-shelled Seaturtles)
  5. Chelydridae (Snapping Turtles)
  6. Kinosternidae (Mud and Musk Turtles)
  7. Testudinidae (Tortoises)
  8. Emydidae (Cooters, Sliders, American Box Turtles)
Figure 1: Phylogenetic Relationships of Turtle Families 
Pleurodira and Cryptodira Testudines 
Within the Testudines, there is a basil split between Pleurodira and Cryptodira.  The two following terms refer to how Testudines hide their heads when they are frightened.  Pleurodiran turtles fold their head either to the right or to the left, and cannot pull their heads into their shells (Fig. 1)(Fig. 2).  Cryptodiran turtles pull their heads into their shells within a pocket, during this process, the turtle's neck curves posteriorly in an "S" shape(Fig. 1)(Fig. 2).

Figure 2: Pleurodira vs. Cryptodira Neck Retraction
Two Pleurodira Testudine Families Examined in Lab:


1) Podocnemidae (Madagascan Big-Headed Turtles & American Side-Neck Turtles)


Location: South America & Madagascar 
Characteristics: 
3 Genera, 8 Species 
Moderately Large
River Turtles
Broad, domed, streamlined shells
Active Swimmers
Herbivores/Opportunistic carnivores
Nest in sand along river 
 2) Chelidae (Australoamerican Side-Neck Turtles) 


Location: South America, Australia, Indonesia 
(Southern Hemisphere only) 
Characteristics:
Flattened Skull and Shell
Primarily Aquatic
Omnivores
Some leave water to forage during rains near water
(Gulp Feeding)                                

Six Cryptodira Testudine Families Examined in Lab:

1)Trionychidae (Soft-Shell Turtles)

 Location: Africa, Asia, New Guinea, SE Asia, Indonesia, North America

Characteristics: 
Snorkel-like snout
Flattened "Pancake"
Reduced Carapace/Plastron
Lack epidermal scutes
Possess thick, leathery skin
Long Necks
Some Possess femoral flaps on plastron




Characteristics
Lattice-like plastron, either fused or separate, hyoplastron and hypoplastron 
Opportunistic carnivores 
Cutaneous Respiration (from not having scales)







2)Cheloniidae (Hard-shelled Seaturtles)
Location: Tropical to Subtropical Oceans
Characteristics: 
Flat streamlined shells with epidermal scutes 
Forelimbs flipper like
Hind limbs webbed for steering 
Emerge on beaches only to nest 
Require 25 years for sexual maturity 

3)Chelydridae (Snapping Turtles)
 Location: Eastern North America, Mexico & Central America, Northern South America
Characteristics:
2 Genera, 2-5 Species
Large Heads (relative to body)
Skull roof deeply emarginated
Broad, flat Carapace
Reduced Plastron (cruciform)
Longest tail of any Testudine
Aquatic, only on lad to lay eggs
Opportunistic carnivores
Primarily Herbivores


**Two genera of Chelydridae are Chelydra (common snapping turtles) and Macrochelys Alligator Snapping Turtle**

  • Biggest difference between the two species is that Macrochelys has four marginal scutes, whereas Chelydra

4)Kinosternidae (Mud and Musk Turtles)
Location: North America, Central America, and Northern South America (New World Only)
Characteristics: 
24 + species 
Smallest Testudines
Oblong, moderately domed carapace
Large heads compared to body size
Plastron commonly hinged
Reduced plastron 
<10 epidermal marginal scutes 
Entoplastron sometimes present
Generally aquatic
Bottom walkers 
Hibernate on land 
Can forage on land 
Occupy underground retreats/nest communally 
Occasionally nest below vegetation  

5)Testudinidae (Tortoises)

Location: North/South America, Galapagos, Africa, Madagascar, Seychelles, Europe, Asia, Indonesia 
Characteristics:
15 Genera, 45+ Species
Almost all have domed shells 
Columnar/Elephantine feet
Terrestrial (Desert, Grassland, Scrub)
100 days incubation to 18 months



6)Emydidae (Cooters, Sliders, American Box Turtles)

    **two Testudine subfamilies within this Testudine family, Emydinae (Fig. 3) and Deirochelinae (Fig. 4)

Figure 3: Subfamily: Emydinae, Genus: Clemmys

Figure 4: Subfamily: Deirochelinae Genus: Graptemys
Location: North America, Central America, Parts of South America, Europe, Asia, North Africa
Characteristics: 
42 species
Medium Sized Turtles
Plastron large, occasionally hinged
Semi-aquatic/terrestrial
Sexual Dimorphism common (females 2X larger than males)
Omnivores or strongly herbivorous 

Two Subfamilies:
1) Emydinae: conservative diets, diversity of habitats, some plastrons hinged 
2) Deirochelinae: Diversity of diets, conservative habitats, aquatic, diet specialists, epipubes do not ossify 


Testudine Anatomy
Skeletons of Testudines are the most unique skeletons of any other type of reptile, because of the presence of a sell structure.  The shell structure is formed by two main skeletal structures, the carapace and the plastron.  The carapace (Fig. 5 & 6) is formed of broadly expanded and fused ribs and vertebrae in the trunk region, as well as a layer of dermal bones that span the spaces between these bones.  The plastron (Fig. 5 & 6) is composed of several paired bones that are remnants of the sternal elements and perhaps the gastralia.  Positioned within the shell structure are the pectoral girdle and forelimb, and the pelvic girdle and hind limb. 
        
           Bones of the Carapace: (Fig. 5 & 6)                                     Bones of the Plastron: (Fig. 5 & 6)
           Nuchal                                                                                     Epiplastron
           Peripheral                                                                                Endoplastron
          Neural                                                                                      Hyoplastron
          Costal                                                                                      Mesoplastron
          Suprapygal                                                                              Hypoplastron
          Pygal                                                                                       Xiphilplastron 

Figure 5: Bones of Carapace and Plastron 



Figure 6: Bones of Carapace and Plastron examined in Lab 2: Testudines 

Overlaying the bony skeleton of Testudines is a thin layer of epidermis.  This epidermis produced large plate-like scale, referred to as scutes (Fig. 7 & 8).  

Scutes of the Carapace (Fig. 7 & 8):                                 Scutes of the Plastron (Fig. 7 & 8):

Cervical                                                                                Intergular 
Marginal                                                                              Gular  
Supramarginal                                                                     Axillary 
Vertebral                                                                             Humeral
Pleural                                                                                 Pectoral 
                                                                                            Abdominal
                                          Inframarginal
                                 Inguinal
                                 Femoral
                           Anal

Figure 7: Scutes of the Carapace and Plastron 



Figure 8: Scutes of the Carapace and Plastron examined in Lab 2: Testudine

Girdle of Testudine 

Figure 9: Pelvic Girdle of Testudine 
Figure 10: Pectoral Girdle of Testudine 

                                   Testudine Skull



Testudines have the skull condition known as an Anapsid skull (Fig. 11 &12).  Although Testudines demonstrate the Anapsid skull condition, many Testudine species have a deep temporal emargination on the posterior margin of the skull. 

Figure 11: Anatomy of Testudine Skulls examined in Lab 2: Testudines

Figure 12: Skull Anatomy of Testudine


Reproduction
Exhibit internal fertilization
Direct Development of embryos inside a cleidoic egg
Shell is hard or pliable and composed of calcium carbonate shell units
All are Oviparous

Males
1.Typically have a concave or slightly concave plastron to prevent them from sliding off females (Fig. 13)
2. Males typically have longer forelimb claws (Fig. 14)
3. Males have a very large copulatory organ, the intromittent organ, its purpose is like a penis to transfer sperm (Fig. 15)

A good way to tell difference between male and female Testudines is by examining the tail. Males tales will be fatter and more robust than the females, and when the tail is gently straightened, the cloaca will be exposed, clearly behind the posterior edge of the carapace, while the female cloaca is positioned at or before the posterior edge of the carapace (Fig. 16).
Figure 13: Comparison of Male Testudine and Female Testudine Carapaces
Figure 14: Presence of Longer Forelimbs on Male Testudines 

Figure 15: Presence of Intromittent Organ in Testudines
Figure 16: Male Chelydra (Visual of Cloaca Posterior to Carapace)
The Arrow here point to the exposed cloaca, based off the position, this is a male Chelydra (common snapping turtle)


Ohio Diversity of Testudines 

Chelydridae (Snapping Turtles):
Chelydra serpentina (Common Snapping Turtle) 


Kinosternidae (Mud & Musk Turtles):
Sternotherus odoratus (Stinkpot Turtle)
Trionychidae (Soft-Shell Turtles):
Apalone spinifera (Spiny Softshell Turtle)
Apalone mutica (Smooth Softshell Turtle)
Emydidae (Cooters, Sliders, American Box Turtles & Allies):
Chrysemys picta marginata (Midland Painted Turtle)
Clemmys guttata (Spotted Turtle)

Emydoidea blandingii (Blanding’s Turtle)
Graptemys geographica (Map Turtle)
Graptemys pseudogeographica (False Map Turtle)
Pseudemys concinna (Hieroglyphica River Cooter)
Terrapene carolina (Eastern Box Turtle)
Trachemys scripta (Red-Eared Slider)

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