Lecture 16 Notes
Lecture 16 Notes 81463 - BIOL 3030 - 001
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This 5 page Class Notes was uploaded by Abigail Towe on Friday October 30, 2015. The Class Notes belongs to 81463 - BIOL 3030 - 001 at Clemson University taught by Richard W. Blob in Fall 2015. Since its upload, it has received 26 views. For similar materials see Vertebrate Biology in Biological Sciences at Clemson University.
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Date Created: 10/30/15
Lecture 16 Reptile Diversity Part 1 Quick review 0 Amniotes of tetrapod lineage but NOT dependent on aquatic habitations gt they can livereproduce anywhere 0 features amniotic egg astragalus more sacral bones in vertebrae to help them move on land a Synapsid mammals like humans a Sauropsids turtles lepidosaurs and archosaurs I lepidosaurs tuatara lizards snakes I archosaurs crocodiles birds nonavian dinosaurs o has two types of fenestra holes in skull I anapsids no temporal fenestra a this is primitive and all extinct I diapsids two temporal fenestrae on each side a there are living species a one example crocodiles risk of being extinct o and TURTLES Turtles are unique o in relation to other sauropsids there are two hypothesis over turtles o 1 the phylogeny shows that turtles are anapsids sister group to all reptiles based on lack of temporal fenestrae o 2 more widely accepted turtles are diapsids and the outgroup I the are part of diapsid clade but lost temporal fenestrae as the skull modified Fossil Turtle o looks like a lizard but the ribs are expanded and positioned like a turtle39s a most fossil turtles have basic turtle body design shell Turtle facts a about 310 species that range in how they eat live etc o can be terrestrial freshwater marine o Another difference between turtles is the mode of neck retraction when they are scared they want their head inside their shell o Clade Cryptodira hiddennecked turtles that bends neck in vertical plane to completely hide head I however some extant cryptodires have lost ability to retract head sea turtles and snapping turtles o Clade Pleurodires side neck turtles that bends head in a horizontal plane so it doesn t hide head completely Other Major Clades of Turtles chelydridae snapping turtles forceful bite cannot hide head in shell completely cheloniidae sea turtles cannot hide head in shell completely carettochelyidae carettochelys limbs have evolved into flippers trionychidae trionychidae softshells like skin emydidae emydidae pond turtles testudinidae tortoises Turtle Synapomorphies 1 shell a bony skeleton covering i covering made from keratinized scutes or skin 1 keratin scutes overlap of bony sutures to add strength b carapace upper shell vertebrae is fused to shell gt cannot move body side to side can only move their limbs i flattened shells aquatic species 1 1 to streamline to reduce drag and cost of swimming river has lower drag faster flow lake has higher drag slow flow ii domed shells terrestrial species adaptation against predators because it makes it harder for predators to get mouth around entire shell iii excepts to general pattern of having flat or domed shell 1 African pancake tortoise has shell that flat but soft and flexible to help them cram their body in rocks to hide from predators Once crammed inside it brings in their limbs and inflates body so that it wedges itself in there 2 shell kinesis shell moves box turtle has a flap on underside that allows the entire body legs and head to be placed inside shell and closes until it s completely safe c plastron lower shell d shell shape varies 2 limb girdles deep to ribs a ribs deflect laterally as they develop grow i the ribs continue to grow until they grow over the shoulder girdle gt the shoulder girdle becomes inside ribs 3 no teeth keratin beak only but still provides forceful bite Turtle Locomotion o terrestrial tortoises o walks on digits but has fat pad elephantine club feet 0 aquatic o freshwater turtles I forefoot paddle with different degrees of webbing I aquatic locomotion rowing swimmers 0 good for accelerating and lowspeed maneuvering 0 uses forelimbs and hindlimbs 0 sea turtles I forelimbs flippers I locomotion flapping swimmers o aquatic flight liftbased thrust updown movements 0 continuous thrust good for long distance swimming beneficial since they migrate and travel long distances 0 not good for maneuvering at low speeds or accelerating o only use forelimbs Turtle Feeding 0 can be carnivorous herbivorous or omnivorous o tortoise herbivores 0 sea turtles mostly carnivorous o aquatic turtles can catch food on land but can only feed if they go into water 0 Example 0 alligator snapping turtle uses tongue to act as a worm to attract fish Turtle Circulation 0 heart two atria but with 3 chamber ventricle o Typically the heartlung relationship is two circuit system pulmonary blood goes to lungs and systemic blood goes to body and it s a sequential process o But turtles can choose to shunt which shifts blood between circuits 0 turtles dive so they don t send deoxygenated blood to lungs because it s not like it can become reoxygenated 0 use intracardiac shunt to move blood from pulmonary circuit to systemic circuit Respiration o contracts muscles and moves lungs to facilitate breathing because they don t have diagram The movement of limbs and girdles change the body cavity volume 0 has cloacal respiration to allow oxygen uptake while diving in water 0 water enters cloaca to pump water in uptake oxygen and then exchange for new water 0 this allows them to dive for much longer times 20x longer time periods reproduction and nesting 0 internal fertilization o for terrestrial males males have penis and their plastron is concave to fit over females to reach cloaca o nesting behavior 0 majority of females lays eggs on land because embryos die if below water 0 can use embryonic diapause o a pause in development until environmental trigger temperature good or ready food Temperaturedependent sex determination TSD c this process occurs in most turtles all crocodilians some lizards and tuatara 0 effects of global warming 0 as temperatures increase the sex determines one sex over another and leads to ex nc on lmpring o females return to their natal beach because sea turtles imprint on that specific beach 0 hatchlings are very small and hardly survive because predator saturation Orientation and Navigation 0 sea turtles use 3 primary cues at different life stages 1 light and elevation gradient to enter ocean 2 waves movement away from coastline 3 magnetic field used during migration through North Atlantic Gyre to help them come back to where they were born homing ability Conservation 0 endangered of extinction 0 one reason they don t reproduce right when they are born takes about 15 years to reach maturity 0 other reasons I habitat destruction 0 logging developments beach development brings in more lights to distract them and vehicles I poHu on o leatherback confuse jellyfish with balloons trash I overcollection for food and pets
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