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Bio 125 lecture #19 (4/4/17)
I.
Phylum Chordata
Phylum Chordata, Class Reptilia
A. Phylum Chordata
1. Phylum characteristics
2. Subphylum Vertebrata characteristics
B. Reptile Orders
1. Order Chelonia: Sea turtles
a. Characteristics
b. diversity
c. Reproduction
d. Threats
2. Order Squamata
a. sea snakes
b. Marine Iguana
3. Order Crocodilla
Phylum Chordata Subphylum Vertebrata
Phylum Chordata
Class Reptilia: Marine Reptiles
Photo courtesy of Ann Burke and Brian McOmber hawaii.edu
Marine Reptiles (Class Reptilia):
General Characteristics
Order Chelonia: Sea Turtles
1. Scales - Prevent water loss
-Mobile armor
2. Ectotherms
3. Breath air
4. Efficient
kidneys
5. Oviparous; leathery eggs
6. Lay eggs on land
Only 8 species – all threatened
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Sea Turtle Characteristics
1. Body in shell (carapace), fused to backbone
3. Shell flattened/streamlined
(Cannot retract head into shell)
2. Bones
lightweight/spongy
(buoyancy)
Sea Turtle Characteristics
Sea Turtle Characteristics
4. Front legs modified into flippers
Rear legs for steering/digging
5. No teeth, but strong biting/crushing jaws
Leatherback (Dermochelys coriacea)
6. Salt glands (turtle tears)
Green sea turtle (Chelonia mydas)
Sea Turtle Reproduction
Long migrations to remote, sandy beaches
Green Turtle nesting sites
https://www.youtube.com/watch?v=ZS0kXtmXuj8
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Nesting
Sea Turtle Reproduction
Fertilization internal
(pair mate)
& in water
Only female goes ashore
Arribada= nesting area
Nesting
Shells soft & leathery
Dig hole with flippers
100-200 eggs per clutch
Multiple paternity
per clutch
Multiple clutches
Hatch in ~60 days
Buried in sand
Colder temperatures produce males.
Warmer temperatures produce females.
Intense predation
Babies dig out of sand
at night –head to sea
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Threats to Marine Turtles
1. Direct fishing/egg collection (food & jewelry)
Threats to Marine Turtles
2. Gill & shrimp nets
3. Trash
Class Reptilia:
Order Squamata (Sea Snakes)
Threats to Marine Turtles
4. Coastal development
Carnivores
with venemous
fangs
Ovoviviparous
(most)
Overexploited for
skins
5. Climate change
Laterally flattened tail
http://www.youtube.com/watch?v=yWapdbAMPa8
• Nostril placement
• specialized valves to close during dives
Olive sea snake
Most sea snakes are ovoviviparous (internal eggs)
Coral snake
(terrestrial relative)
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Order Squamata: Marine Iguana
Galapagos only
Laterally flattened tail
Class Reptilia: Marine Iguana
Salt glands
Herbivore– dives 33 ft
Class Reptilia:
Order Crocodilla (saltwater crocodile)
• mangroves, estuaries
• max 33 ft! (usually <20 ft)
• most aggressive marine animal
Lecture #19 (4/4/17): Class Reptilia
1. List the 5 defining characteristics of Phylum
Chordata.
2. List the 4 defining characteristics of Phylum
Chordata, Subphylum Vertebrata.
3. List 5 characteristics that distinguish Class
Reptilia - marine reptiles.
4. Describe an amniotic egg. Be able to identify
the location and function of each of the following
parts of an egg: shell, chorion, yolk sac, allantois,
amnion, albumen.
5. Why did the evolution of the amniotic egg allow
reptiles to become so successful?
http://www.soundboard.com/sb/Crocodile_sounds_audio
6. List 6 characteristics of sea turtles (Order
Chelonia).
7. Describe reproduction in turtles including:
fertilization (internal or external?) & nesting.
8. What human activities have endangered sea
turtles? (List at least 3).
9. What characteristics distinguish Order
Squamata (sea snakes) from terrestrial snakes
(list at least 3)?
10. What type of reproduction do sea snakes
have?
Define: ovoviviparous, oviparous
11. Sea snakes have venomous fangs, but are
rarely a threat to humans – why not?
12. What do marine iguanas eat? What
adaptations do they have to help them get this
food?
13. Where do saltwater crocodiles (Order
Crocodilia) live? What feature allows them live in
such wide ranges of salinity?
14. List the method of salt extraction for each
group of marine reptiles (sea turtles, sea snakes,
marine iguanas, crocodiles)
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