ReptilesThe most magnificent animals…

By Goran Georgiev & Dimitar Drumev 10/3

What are reptiles? Reptiles are a group of furless amniotes.

Amniotes were early tetrapods that could

survive in much drier environments.

They would lay amniotic eggs. These had

an amniotic membrane around them.

Ancestors of birds, mammals, reptiles.

http://upload.wikimedia.org/wikipedia/commons/8/83/Tortoise-Hatchling.jpg

What about them?

Reptiles have a bilateral symmetry.

Most closely related to mammals.

Easily distinguishable by their scales.

Most lay their eggs on land.

Most reptiles are also ectothermic.

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Clades There are a lot of extinct reptiles. Generally

divided into these 4 orders: Crocodilia (alligators and crocodiles) - 23

species Sphenodontia (tuataras from New Zealand) -

2 species Squamata (lizards, snakes, and worm lizards)

~ 7,900 species Testudines (turtles and tortoises) ~ 300

species

Where do they belong?

The oldest common ancestor they had

with humans was 530 MYA.

They belong to the Chordate phylum.

Chordates are very complex and

evolutionary advanced

animals that have a backbone.

http://christiansotophoto.com/Reptiles%20and%20Amphibians/arles_gallery/images/Reptiles-04.JPG

How do they move?

Most tetrapods simply walk with legs.

Snakes and legless lizards sliver on the

ground in an S motion.

Some reptiles can glide in the air.

Most reptiles are also excellent

swimmers.

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What about reproduction? Fertilization is internal and then the

eggs are laid (or oviposition) Some are viviparous – they bare live

young. Others lay eggs inside themselves, the

eggs hatch and then the female gives birth (gravid).

Nervous System Same basic parts as all amphibian brains.

Sense organs are developed except for

snake’s lack of ears.

Most brain analysts suggest they are less

intelligent than mammals or birds.

Excluding crocodiles, brain to body

proportions are very small.

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Pelochelys cantorii – Cantor‘s giant soft-shelled turtle

Grows up to 2 meters in length.

Fresh water predator turtle that

feeds on fish

It is endangered. Lays ~30 eggs in the

first quarter of the year.

Spends 95% of life buried and motionless.

http://indobestseller.files.wordpress.com/2009/10/soft-shelled-turtle.jpg

Ophiophagus hannah – King Cobra Longest venomous snake – 5/6

meters long.

Dedicated parents – one of few

snakes to stay with its eggs.

Very fierce and agile predator.

Produces huge amounts of venom in just

one bite.

http://www.becks.com/wp-content/uploads/2009/05/king-cobra.jpg

Crocodylus porosus Saltwater crocodile Largest of all living reptiles.

Found in India, Asia and

Northern Australia.

Species can weight more than 1250kg and be

6 meters in length.

Their diet consists of sharks (including bigger

ones), kangaroos, monkeys and wild boars.

http://biscottisandkangaroos.files.wordpress.com/2009/03/saltwater-crocodile.jpg

Humans & Reptiles We are the reason for the

endangerment of a lot of reptiles. We use alligator skin to make bags,

wallets, belts, etc. Some reptiles considered delicacies in

certain countries. Snake venom sometimes used in

medicine.

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Trivia What does the Bulgarian word рептили (reptili) mean?

Which statement about snakes is NOT true?

A. Snakes never stop growing.

B. You can tell the age of a rattlesnake by the number of

its rattles.

C. Snakes are found on all continents except Antarctica.

D. There are approximately 2700 species of snakes in

the world.