Anatomy and Development
Anatomy and Development WFS 462
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This 3 page Class Notes was uploaded by Dani on Friday January 23, 2015. The Class Notes belongs to WFS 462 at Pennsylvania State University taught by Avery in Spring2015. Since its upload, it has received 639 views. For similar materials see Herpetology in Wildlife Studies at Pennsylvania State University.
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Date Created: 01/23/15
0 Anatomy 0 I O I I I Direct b o What is a larva Aquatic l I Hatching O O Herpetology notes 12215 Pond forms of amphibians will have larger gills with more surface area Less oxygen available than in streams Development amphibians mostly Most frogs have external fertilization Internal fertilization in all caecilians reptiles and most salamanders orn looking like mini adults vs indirect larval Reptiles direct o More yolk in egg to sustain animal longer Amphibians can be either Meso vs macrolecithal eggs 0 Meso only permits indirect development 0 Macro permits direct development Protective barriers Externally deposited embryos need more pretention o Gelatinous masses in ponds 0 May protect from UV radiation and desiccation Protection from predation 0 Both meso and micro predators Early stage after hatching that differs in appearance to adult form In egg embryo Direct development juvenile at birth Free living embryos Most feed during this period but some live off stored yolk Many are aquatic Undergo a serious transformation to become adult 0 Anurans tadpole to frog arvae 0 Thin heavily vascularized skin 0 Pharyngeal slits and gills o Gills persist in lower forms of anurans caecilians and salamanders Gills replaced in frogs Lidless eyes Cartilaginous skeletons Lateral lines Poorly understood across all groups Some have hatching glands that help dissolve gelatin capsule Tadpole morphology Oral disk Spiracle O O Reptiles o Hind limb bud 0 Location of mouth parts surface feeding vs suctorial o Operculum limbs emerge here Eggshell imposes limits 0 Cannot survive submerged in water Water absorption through shell allows the embryo to increase weight from original ovum weight 0 Water availability affects rate of development and size of hatchlings Nest sites MUST be chosen carefully o Substrate for buried eggs is very important 0 Must permit gas exchange 0 Soil permeability o Friability ability to crumble Temperature is critical 0 Cold can slow development resulting in suboptimal emergence time 0 Can also be true for amphibians 0 Warm results in increased metabolism 0 Depletion of yolk Metamorphosis does not occur in reptiles o Hatch as miniature adult Hatching 0 Extract calcium during development 0 Makes shell weaker 0 Some turtles have delayed emergence Growth 0 Influenced by quantity and quality of food 0 Temperature influence 0 Metabolism speeds 0 Sex determination o Grow faster in warm slower in cold to a certain degree 0 Food shortage influence 0 Estivation 0 Low activity status to preserve nutrients o Ectotherms can exist better in harsher environments than endotherms o Ectotherms exhibit close to indeterminate growth Age at sexual maturity VARIES o 4 months 7 years 0 2 months 40 or more years 0 Not solely due to size 0 Larger individuals can have larger clutch sizes 0 Smaller individuals may need to have young faster prey species Metamorphosis Thyroxine TH causes this process 0 Crowding O O 0 Reduced food 0 Reduced oxygen 0 Drying of water bodies 0 Predation Ecdysis shedding skin I Amphibians o Tend to shed once per week I Crocodilians and turtles 0 Cell growth is continuous and skin is shed continuously nonshelled portions 0 Turtles can retain or shed scutes seasonally I Lepidosaurs reptiles with overlapping scales 0 Shed patches to entire piece 0 Growth and shedding phase 0 Renewal lasts about 14 days Coloration I Amphibians o Pigment cells 0 Chromatophores I Melanophores lighten or darken the colors I Iridophores stacked purines blues and greens I Xanthophores pteridine pigments yellow orange red 0 Color largely determined by pigment in xanthophores and reflectivity in iridophores 0 ANATOMY USED IN CLASS 000 Nasolabial groove groove that runs from nostril down to lip Costal grooves flanking sides Dorsolateral fold ridge that runs down either side of back Parotiod glands frogs