Reptilia

Question 1

What are the shared characteristics between reptiles?

Answer 1

Scales made up of waterproof keratin, helping prevent dehydration in dry air
Breathe using lungs
Amniotic egg - major diagnostic feature that distinguishes reptiles from amphibians

Question 2

What are the four orders of living reptiles?

Answer 2

Testudines - 300 spp.
Squamata - 9400 spp. 95% living reptiles
Crocodilia - 23 spp.
Sphenodonta - 2 spp. Restricted to small islets of New Zealand, slow growth and reproductive rate

Question 3

Define the testudines

Answer 3

Shell consists of two layers, outer keratin and inner bone
New layers laid down as turtle ages
Bony layer is a fusion of ribs, vertebrae and other bony elements
Lack teeth instead have keratinised plates
All turtles bury eggs in the ground, temperature can effect the sex of the offspring

Question 4

Name a study that shows temperature has an effect on sex of reptiles

Answer 4

Lang and Andrews 2005 - shows temperature can have an effect on crocodilian species

Question 5

Define the squamata

Answer 5

Largest reptile group containing over 9000 species

~6000 species of lizard and 3000 snake

Question 6

Key points about lizards

Answer 6

Lizards - occupy all continents except Antarctica as well as most oceanic island chains
Most have movable eyelids
Most have 4 limbs although some are limbless (glass lizards)
Well developed colour vision
Many can automotise their tails to escape from predators
Most are oviparous
Parthenogenesis occurs in around 50 species of lizard

Question 7

Name the only known venomous lizards

Answer 7

Gila monsters (Heloderma suspectum) 
Beaded lizard (Heloderma horridum)
Komodo dragon (Varanus komodensis) Fry et al 2009

Question 8

Describe the snakes

Answer 8

21 families ~3000 species
Extremely elongated body, limbless, kinetic skull
Specialised organs - Jacobson’s organs (chemoreceptors) and pit organs (thermoreceptors found in pythons and boas)
Less than 20 percent of snakes are venomous, use either neurotoxins or haemotoxins
Most snakes are oviparous but some are viviparous

Question 9

Describe the crocodilia

Answer 9

Elongated, structurally reinforced skull
- wide gape, powerful jaw muscles, teeth set in sockets
Mother guards young for 2 years or more
Oviparous
Adults have No real non-human predators
Crocodiles tend to be more aggressive than alligators
Crocodilia posses special sensory organs that make their skin hypersensitive allowing them to detect prey in the dark and different temperature zones with ease. These are known as integumentary sensory organs (ISOs)

Question 10

What are the 4 layers of the amniotic egg?

Answer 10

Amnion - formed from inner membrane of amniotic fold, encloses fluid filled cavity.
Yolk sac - provides food for complete development, no larval stage
Chorion - formed from outer membrane of amniotic fold, grows to protect embryo and yolk
Allantois - grows from hind gut, between amnion and chorion. Functions in respiratory exchange through porous she’ll

Question 11

How many species of reptilia are there? And describe their evolution

Answer 11

~10,000 species
Probably arose from amphibious labyrinthodontia 390mya
Mesozoic era - age of the reptiles 165 Mya