Herpetology - exam 2

Integument

- scales, scutes, plates

- no respiratory function

- conservation of body fluids and water

- protection from environmental factors

- variation between/within clades

- non-scaled = mutation

Epidermis

thick cornified epithelium

Turtle shell

- living tissue

- shell grows as turtle grows

- bulky

Advantage of a bulky turtle shell

- herbivores

- environmental protection

- relationship to turtle respiration

- predator protection

Chelonian epidermis

- beta keratin

- manufactured by the collagen cells on top of the bone

- some turtles shed their scutes

- some turtles layer their scutes and don't shed them

- keratinous structures

Keratinous structures

- claws

- egg caruncle

- tomia

Egg caruncle

keratinized bump used to get out of the egg shell

No scute exuvia: non-shedding turtles

- most box turtles

- tortoises

- African side-necks

- all soft-shells

Retained scute definition

when a turtle's scutes develop faster than they are being shed off

Retained scutes causes

- poor diet

- poor filtration

- improper lighting

- insufficient basking area

- water too warm

Alpha keratin

- flexible keratin over bone

- leatherbacks and soft-shelled turtles

Reptilian epidermis

- oberhautchen

- b-keratin

- a-keratin

- stratum coreum

- stratum germinativum

Options for outer layer of reptilian epidermis

- thicken

- non-overlapping

- overlapping

- separated

Reptilian keratinous structures

- claws

- projections

Reptilian ecdysis - things to consider

- process

- frequency

- causal mechanisms

- duration

- behavioral effects

- occular scale (monocle)

Sheds

- snakes shed in one layer

- lizards tend to shed in sheets

Rattlesnake rattle

- sheds rattle

- not based on age

Glands

- few in integument in reptiles

- scent glands

- musk glands

- cloacal glands

- nuchodorsal glands

- femoral/precloacal glands

Nuchodorsal glands

- turtle glands in neck

- pheromone glands

Femoral/precloacal glands

- lizard glands in thighs

- usually only in males

Pigmentation/coloration

- controlled by pituitary gland

- melanocytes

- chromatophores

Chromatophores

- xanthophores

- melanophores

- iridophores

Pigmentation mutations terms - scientific

- albinism

- melanism

- leucistic

Pigmentation mutation terms - breeders/hobbyists

- piebald

- axanthism

- anerythristic

- "hypo-"

- "hyper-"

Chelonian skull

- holes covered (diapsid)

- nasal bones absent or incorporated

- fused with minor kinetics

- movement at cervical attachment

- powerful 'snap' with beak

- muscle attachments at posterior

Reptilian skulls

- a lot more side to side movement

- many projections on head are actually part of the skull

Two major types of lizards

- scleroglossan lizards

- iguanids

Scleroglossan lizards

- some movement but not a lot

- have a split tongue

- mandible can go down and the maxillary can go up

Iguanids

iguanas, chameleons, geckos

Adaptations increasing the gape of snakes

- mandibles are not fused by bony symphasis

- mandibles include hinge

- elongated quadrates articulate with braincase

- snout is hinged to braincase

Morphogenesis of turtle shells

- shell rudiment cell buds grab the ribs and pull them outside the body

- ribs flatten and become the carapace

Turtle head movement

- primary evolution is the neck scrunching backwards to pull head into shell

- secondary evolution is the longer neck (side neck)

Special vertebrate: caudal autotomy

- tail can come off

- dropping tail costs energy

- some come back to eat tail to regain energy

- urotomy

- fracture planes

- muscle bundle

- regeneration

Urotomy types

- autotomy

- pseudoautotomy

Autotomy

- skinks

- subset of urotomy

- can decide when it happens

- closes off blood vessels so there's little to no blood

Pseudoautotomy

- snakes and lizards

- tail breaks off to protect the rest of the body

- there will be blood

Fracture planes

the area that the tail drops from

Regeneration - autotomy

- size is exact replica of previous tail

- might not be the same color

Regeneration - pseudoautotomy

not a perfect replica, will be more blunt

What happens to constrictor ribs when they eat?

the ribs break and then repair themselves

Tuatara

- tuatara thorax has ribs that have little hooks on them (gastralia)

- seen on a few lizards but lots of dinosaurs

Special ribs: gliding lizards

- live in trees

- have ribs that flatten out to give support

- float between trees

Girdles and limbs

- mainly bones

- pentadactyl

- patella first appears

- rear legs more powerful (longer)

- feet turned directly forward

- elongated and slender limbs

- loss secondarily for burrowing/dense vegetation

Chelonia muscles

- epaxial and hypaxial muscles limited functions

- kinetic functions in neck and head well-developed

- flexor muscles appear in limbs

- rotation and rotation prevention possible

- digits with muscles

Chelonian locomotion

- on land, turtles' gait is ponderous

- terrestrial turtles can move a long way

- aquatic turtles are the swiftest of all living reptiles

Sea turtles appendages

- front appendages push water back

- back appendages used as rudders

Reptilia muscles

- hypaxial less modified

- epaxial more modified

- trapezius appears

- epaxial especially well-developed in snakes

Van derWall

- 90 lbs/square inch can be held by the fingers

- force equivalent to static electricity

- have small ridges with stalks coming off them which are constantly moving

Snake locomotion

- lateral undulation

- rectilinear crawling

- concertina locomotion

- sidewinding locomotion

- scansorial locomotion

Lateral undulation

- most common form of serpentine locomotion

- push against something at multiple points in the body

Rectilinear crawling

- belly acts like a bulldozer on the ground

- grabs on the substance or substrate

- used in bigger snakes like boas or pythons

Concertina locomotion

- anchor a point and pull body towards that point

- anchor a point and push body away from that point

Sidewinding locomotion

- hitting a point and hoping

- there's a gap in the tracks

- used in snakes that live on sand

Arboreal snakes - locomotion

- use concertina while climbing up the tree

- use rectilinear on the tree

Chelonian respiratory system

- no gills

- lungs

- few exceptions

- aquatic species must surface

- high tolerance to anoxia

Chelonian respiratory exceptions

- tissue used as a 'gill'

- oxygen passing through a thin membrane that has a lot of capillaries

Cardio-respiration

- system looks great

- very inefficient

- lungs don't have as much exchange surface

- hearts are not true three chambered hearts

Turtle respiration modes

- gas exchange

- breathing

- special cases

Turtle gas exchange

- lungs

- blood-buffering against CO2

- myoglobin

- tolerance of lactic acid

- slowing metabolism

Turtle breathing

- impossibility of moving ribs or expanding chest cavity

- muscles and viscera pressing on lungs

- moving of the pectoral girdle

Turtle special cases

- pharyngeal

- cloacal bladder

Pharyngeal respiration

soft-shelled turtles

Cloacal bladder respiration

- semi-aquatic turtles (blanding's turtle and painted turtle)

- exchange O2 and CO2 through cloacal bladder

Lizard respiration - lungs

- in pairs, right usually bigger than left

- no diaphragm

- against the back

- lepidosaurs

- iguanians

- veranids

Snake lungs

- right lung is very long

- left lung in very small

Sea snakes - lungs

- pump lungs forward

- 3/4 of the lung is exchange

Rattlesnakes (non-constrictors) - lungs

- heart is halfway through the lungs

- don't need to constrict

Colubrid ratsnake (constrictor) - lungs

- heart is very far forward so it can constrict

- has a long lung with a small exchange area

Snake lung disease

- OPMV (Ophidian paramyoxvirus)

- causes lungs to have dead areas

Blood

- 25% red blood cells

- 2% white blood cells

- plasma colorless

- plasma greenish yellow in rattlesnakes

Reptilia white blood cells

- heterophil

- lymphocytes

- monocytes

- azurophil

- eosinophil

- basophil

Chelonian phlebotomy

- a lot of blood - occipital sinus / jugular vein

- can also go for the arm or the base of the tail

Lizard phlebotomy

- ventral Coccygeal (caudal) vein

- central abdominal vein

Serpents phlebotomy

ventral Coccygeal (caudal) vein

Turtle tomia

- no movement

- no muscles

- just keratin over bone

Buccal cavity - lips

- squamates, lizards, and snakes

- not much movement but do have sheet muscles

- mouth can't do much, just flesh around the area

Forked tongue

- mainly for olfaction

- bring tongue to the roof of the mouth to smell

Iguanids tongue

- very muscular

- manipulative tongue to pick up food

- have taste receptors

Camilidae

- specialized iguanid tongue

- tongue can easily come out 1.5 SVL of the animal

- .70 body weight of the animal

- can come out at a velocity of 5.75 m/s

- can accelerate at 500 m/sec^2

Turtle dentition

- toothless

- can have a serrated tomia

Tuatara dentition

- located on mandible and roof of the mouth

- acrodont on the vomerine bone and mandible

- monophyodont

Lizard dentition

- acrodont: mainly on vomerine

- pleurodont: one row on the maxillary bone and mandible

- majority are unicuspid

Snake dentiton

- pleurodont teeth on the mandible: maxillary teeth that are primarily pleurodont

- palatine teeth on the roof of the mouth: acrodont

- usually curved backwards

- only have one tooth on the maxillary bone which is the fang

- if not venomous, will have teeth on the maxillary bone that will be pleurodont

Snake fangs

- specialized teeth on the maxillary bone

- envenomation dentition

- type of venom-delivery apparatus is more closely related to taxonomy

Venom-delivery apparatus

- opistoglyphic

- proteroglyphic

- solenoglyphic

Opistoglyphic teeth

- fixed, grooved fangs: rear of jaw

- hognose, ringnecks: not considered venom delivery

- colubrids: very venomous

Proteroglyphic fangs

- fixed, hollow fangs: front of jaw

- elapids

- delivers venom very efficiently

Solenoglyphic fangs

- folding, hollow fangs: front of jaw

- viperids

Fangs in vipers/pit vipers

- mouth closed: quadrate rotated backwards maxillary and fang

- mouth open: quadrate rotates down, rotating maxilla and fang into upright position

Oral glands

- lingual

- sublingual

- labial

Labial secretions

- duvernoy's glands (colubrids)

- venom (vipers)

Reptilia labial glands

- helps lubricate and somewhat start the digestion

- in the mandible and inside the maxillary in the roof of the mouth

- inguanid lizards have glands in the tongue

- snakes have a few lingual glands but they are behind the fork of the tongue

Helodermatid venom gland

- lizard has to chew on you to get venom

- tend to get more injured by teeth

- when the grab prey, they hold on and don't let go

Envenomation

- venom varies by species, age, and individual

- venom consists mostly of digestive-type enzymes and a spreading agent

- Viperidae are mostly hemotoxic

- Elapidae are mostly neurotoxic

All venom functions

- primary: securing prey

- secondary: digestion

- lesser additional function: defense

Evolution of venom

- montane vipers eat relatively big food items and cool down at night so...

- snake metabolism would be slower allowing bacterial population increase but...

- deep injection of venom spreads digestion of prey from within

How big snakes control their digestive systems

- turn off during fasts; turn on after feeding

- 'on' increases metabolic rate by 1500-4500%

- metabolic start-up burns an average of 32% of prey-item's calories

- 'off' reduces metabolism to 50% of snake-typical

Digestion

- esophagus

- stomach: all the stomach acids to break down the food

- small intestine: absorbs all the nutrients

- large intestine: bringing water back

- colic cecum: keeps flora for digesting

Metanephric kidney

- over 100 (probably thousands) of nephrons

- spherical, smooth in lizards

- elongated cylinders, rugose in snakes

- rounded, somewhat smooth in turtles

Mesonephrons

- tubules form in middle section of kidney

- tubules open into mesonephric duct

- pronephros regresses

- present and active in all embryos