Niche Species Anatomy Online Practical

REPTILES

REPTILES

what is the purpose of the dorsal/later scales on a snake?

to display color variation for camouflage

what is the purpose of ventral scales on a snake?

- larger in size

- used for movement + to feel ground vibrations

where is the vent scale and what is it?

- ventral aspect near the tail

- opening for the cloaca

what are little spikes just below the vent called?

vestigial spurs (remnants of the pelvis/femur bones)

Identify the different features in this image

What is the function of infrared receptors/pits in some snake species (e.g. royal pythons)?

helps the snake to sense warm blooded prey and strike with accuracy even in the dark

what is the open slit-like structure on the upper inside of a snake’s mouth

Choanal Slit

what does the Choanal Slit house?

Jacobson’s organ

what is Jacobson’s organ?

a special sensory structure with paired openings in front of the snakes choanal slit

what is the name of the line that is visible externally beneath the lower jaw?

Mental Groove

where does the mental groove run on the body?

center of lower jaw bones to the throat

how many rows of teeth do snakes typically have

6 rows of teeth - 4 upper rows & 2 lower rows

what is the function of the Jacobson’s organ?

detects odors and pheromones

How do snakes smell things?

- flicking their tongues - allows tongue to pick up minute scent particles in the air

- tongue brought back into mouth and particles transferred into Jacobson’s organ

How are snakes able to open their mouths wide enough to swallow their prey?

interscale skin unfolding → mental groove folds in → epidermal cells less packed →

dermal skin stretches → stretching of elastin in deep dermis → mouth is able to open wider to ingest prey

Identify these structures

Top = Choanal slit housing Jacobson’s organ

Bottom = glottis

what do you do when a snake latches onto you?

DO NOT PULL SNAKE

run them under cold water

where should incisions on a snake be made?

via paramedian incision (at the junction of the lateral and ventral scales)

(helps avoid hitting the large ventral abdominal vein)

what is the BCS of this snake? 

Obesity - copious amounts of fat would be seen all the way up the body internally

Externally - cant see spine clearly, fat rolls, appearance of “hips”

what is the BCS of this snake? 

Underweight

Internally - hardly any fat bodies

Externally - spine visible, neck thin + wrinkly, no thick point to body

Identify these structures

This is a fresh dissection of a snake. Identify the different internal organs in this snake

What is the function of the cranial region of the lung compared to the caudal region?

Cranial is vascularized and functions in gas exchange

Caudal mainly functions as air sac & non-respiratory

what important process is regulated by the thyroid gland in the snake?

Ecdysis (skin shedding)

Do snakes have a urinary bladder?

No - ureters feed into the urodeum of the cloaca

identify the structures of this embalmed species

describe the location and appearance of the thyroid gland in the snake

- cranial to the heart

- spherical + red/pink color

how many chambers does a snake heart have?

3 chambers - 2 atria, 1 ventricle

how many sections is the ventricle divided into?

3 sections

which veins carry deoxygenated blood to the sinus venosus?

left hepatic vein

left and right precaval veins and

post caval vein

what is the name of the 3 ventricular sections?

1. Cavum arteriosum

2. Cavum pulmonae

3. Cavum venosum

what is the function of the cavum arteriosum?

receives oxygenated blood from left atrium

what is the function of the cavum pulmonae

ventral to the other two, blood passes to pulmonary artery from here

what is the function of the cavum venosum

receives deoxygenated blood from right atrium

identify the structures in the image

ventricle, left atrium, right atrium, thyroid gland 

what color are the intestines in chameleons?

pigmented black

which liver lobe is larger in lizards?

left liver lobe

where precisely are the kidneys located in reptiles?

caudal coelom within the pelvic canal

do all lizards have a urinary bladder?

no, some species of lizard do not have a urinary bladder

what is the function of the renal portal system in reptiles?

supplies blood to renal tubules - particularly when glomerular filtration is reduced

helps maintain kidney function and may protect against ischemic damage / necrosis

Why is UVB light important in reptiles?

enables natural synthesis of vitamin D3 in skin = essential for calcium absorption and metabolism

what are reptiles at risk of developing without adequate UVB exposure?

metabolic bone disease - weakens bones and overall health

What is the meaning of ectothermic?

rely on external sources of heat to regulate body temperature

define dysecdysis

abnormal shedding of skin

identify these structures

identify these structures