Science Investigative Project

• Duckweed (Lemna)

Preparation of Materials

• 2 culture containers (basins or bowls) of equal size

• 20 fronds of duckweeds

• Pond water

• Record Notebook

• Pen

• Marker

Reptiles

Characteristics of Reptiles

• Amniotes- “amnions”-elastic sac where the embryo develops.

• Most are oviparous but some are viviparous.

• Skin covered by scale or scutes.

• Ectothermic

Characteristics of Reptiles

• All have three chambered heart except for crocodiles which have four.

• Absence of gill even during the juvenile stage but presence of well developed lungs.

• Ear holes instead of external ear

Group of Reptiles

Orders of Reptiles

Order Crocodilia Order TestudiniaOrder SquamataOrder Rynchocephalia

Order Crocodilia

• Semi-aquatic predators

• Extra transparent eyelid

• Flap of skin at the back of their throat.

•Carnivorous

Characteristics

•Diapsids-two holes on each side of the skull.

•Oviparous

•Eyes on top of the head.

•Laterally compressed teeth

Characteristics

•Nostril at the tip of the snout.

Order Testudinia

• Upper and lower bony shells surrounding their body.• Carapace-Dorsal

• Plastron-Ventral

Characteristics

• Absence of teeth instead keratinous beak.

• Oviparous

• Young are independent of the parent at hatching.

• Temperature sex determination

Order Squamata

•Lizards

•Snakes

•Worm Lizards

Lizards

• Two pairs of legs

• Upper and lower laws unite anteriorly

• Most are oviparous some are ovoviviparous

The only venomous lizard

Gila Monster (Heloderma suspectum)

American Beaded Lizard (Heloderma horridum)

Snakes

• Limbless but some have traces of hind limbs (python and boa)

• Internal fertilization

• Joints between vertebrae

• Jacobson’s organ or vomeronasal organ

• Movable upper jaws and loosely joined lower jaw

Worm Lizards

• Specialized burrowers

• Single median tooth in the upper

• Legless and skulls are wedge or shovel shaped

• Skin have ring like folds called annuli

• Oviparous

Order Rhynchocephalia

• Two rows of teeth on the upper jaw and one row of teeth on the lower jaw.

• Oviparous