Herp Exam 2

Herp Anatomy and Physiology

Integument- why is it important

Skin!!
-Covering (holds everything in)
-Prevents desiccation
-Protection
-Defense
-Camouflage
-Gas exchange (esp. amphibians)
-Transportation
-Home for babies
-Food for babies (caecilians)
-Thermoregulation
-Mate attraction / advertisement
-Protection against disease

3 ways Amphibian Integument differs from fishes

1. Surface Layers are cornified
--Amphibians come out of water more so they have a little more protection
2. Multicellular Glands lie below the dermis
--Mucous glands that keep them moist
--Posion / Granular glands for defense
3.Scales are practically absent
--Some dermal scales in caecilians (correspond with annulation)
--Osteoderms in Phyllomedusa, Gastrotheca, Megophyrs (pojections in the skin)

Most skin with 2 layers

Epidermis = outermost layer
Dermis = inner layer, thicker, more stuff in it

Cornified

dead skin with a lot of keratin in it that provides protection;
=thin outermost layer that's tough and made of dead cells;

Amphibian Breeding Cornifications

thickened epidermal patches that are cornified -- helps them amplexus ; may slough off after breeding season

Characteristics of the Amphibian Epidermis

- Stratum corneum is sloughed in all amphibians
- Generally non-vascular, but depends on respiratory mode (i.e, if depend heavily on cutaneous respiration)

Stratum Corneum

outermost layer of epidermis constantly replacing itself
-In Bufo, sloughed off in one unit
-Slough is often eaten (AUTOPHAGY)

Hairy Frog Trichobatrachus robustus

Vascular epidermal protuberances; epidermis vascular for gas exchange in these projections;
-Tricho = hair
-Structures = epidermal protuberances that develop during breeding season to increase area for gas exchange (breeding season is intense and energetically expensive)

Hellbender (Cryptobranchus alleganiensis)

Highly aquatic salamander- wrinkly to increase surface area for gas exchange in the water

Epidermal Modifications

-Setae: skin suction cups on toepads (Treegrogs (Hylidae), Eleutherodactylidae)
-Spades: cornified areas on rear feet that help them dig (Spadefoot Toads- Scaphiopus, Spea)
-"Claws": African clawed frogs (Xenopus)--not a true claw though
-Nupital Pads: develop during breeding season that helps males grasp females in amplexus (Ranidae, Bufonidae, Hylidae)
-Rasping lips: keratinized lips for scraping algae off of rocks etc.- many frog larvae
-Spines and Tusks

Anuran Amphibian "Claws"

Not true claws, really just thickened cornified end of the epidermis on ends of digits
-Used to shred their food; males may stab eachother with them
--True Claws: sheath that encases digits

Anuran Amphiian Prepollical Spines

Pollic = thumbs; under skin in some spp. , can pop them out of skin during fights
-Jab each others eyes with them

Anuran Amphibian Nuptial Pads

Thickened areas on thumbs that help with hanging on to females
-In some, hypertrophy of forearms

The Dermis

-Structural Proteins
-Nerves
-Vascular Supple
-Chromatophores

Chromatophore

pouch of pigment, helps with color change;
-Usually arranged in a dermal chromatophore unit:
--Yellow/ orange top, iridescent/blue middle, black/ brown bottom

Dermal chromatophore unit

Superficial:
--Xanthophore (pteridine = yellow pigments) OR Erythrophores (Carotenoid = orange pigments)
--Iridiophores (=guanophores) (purines = reflect light, blue or green)
Deep:
--Melanophores (Eumelanin pigment)

Color pigments are

Either synthesized by organism / sequesterd from food
--Yellow / orange pigments (Pteridine & Carotenoid) usually from food
--Iridiophore pigment synthesized from organism themselves

Color of Amphibians

All amphibians have chromatophores, but variation in the ratios of pigments, and not all change color;
-All often mediated by MSH (Melanophore Stimulating Hormones)

Melanophores

Extensive dendritic processes
-Darken: spreads out pigments
-Lighten: concentrates in middle of melanophore

Glands are _____ in origin and all are ______

epidermal; alveolar:
flask-shaped- opening in epidermis, mucus / poison contained in flask that sinks in dermis

All amphibians with 2 types of glands

-Mucous
-Granular: strong toxins are often driven by coevolutionary arms race

Gland Modifications

-Warts: concentrations of granular glands
-->Parotid Gland: expresses a lot of poison
-Hedonic/ Mental Glands- concentration of pheromonal glands derived from both mucous and granular types
-Nuptial Excrescences: concentration of mucous glands on thumbs of Anurans and rear limbs of many salamanders (makes them sticky so they can hold on more)
-Poison Glands- produce a wide range of chemical toxins

Mental Courtship (Hedonic) Glands

In salamanders- rely heavily on pheromones
-A lot of them have external fertilization; ale spermatophore and try to get female to go over it
-->A lot of salamanders have conentrations of glands on their CHINS- used to transfer pheromones

Type of Poison depends on

Species
-Biogenis amines (serotonin, epinephrine, dopamine)
-Bufodienolides
-Steroidal alkyloids (e.g. Batrachotoxins)
-Unique polypeptides

Poison Dart Frogs (Dendrobates tinctorius)

Brightly colored and super Aposematic

Spines and tusks on Anura and Caudata

Teeth / spines on / near mouth breeding season --> agressive interactions or for mating
-Emei Mustache Toad (Leptobrachium boringii): labial spines on males

Water Relationships for Amphibians

Super important! Permeable skin; depends on cellular concentrations -- salt etc.
-Osmosis = process by which water is transported across membrane
-->works on a concentration gradient- usually higher concentration -- movement across membrane to dilute concentration

5 Generalizations of Amphibian Osmoregulation

-Produce copious and dilute urine
-Kidneys can control water loss-- pull out as much water as they can when producing waste
-Tubules can actively move ions (Na+)
-Thin Skin (highly permeable membrane)
-Bladder Storage is Important -- store a lot of water in their bladders

Great Plains Toad (Bufo cognatus)

can store 30% of body weight in bladder water
--Live in dry environments so hang on to water as long as possible

Cutaneous water loss is ________

Temperature Dependent;
-Higher temp = faster water loss
-->This is why amphibians don't bask
--Response to water loss during the day would be to be active at hight -- a lot of frogs and salamanders active at night when it's cool and moist
-Plethodon: water loss can be up to 50x that of lizard of comparable size

How much water an an amphibian lose?

depends on the species --> more terrestrial species can tolerate more water loss
--Terr. --> Aquatic:
-Scaphiopus
-Bufo
-Hyla
-Rana
*No difference between water loss RATES, only in TOLERANCE to loss

Amphibians and Sodium

-Amphibians can excrete Na+ and can actively uptake Na+ from the environment
--> helps with moving things across the skin
-Special tubules surround blood vessels in kidneys allowing for Na+ transport across membranes

5 Water Conservation Adaptations

1. Waxy Skin Secretions
2. "Tanking up"- specialized 'pelvic patch'
3. Postural adjustments
4. Uricotelism- excreting uric acid
5. Ureutelism - excrete urea

Waxy Monkey Frog -- Phyllomedusa sauvagii

waxy skin secretions allow them to tolerate direct sunshine for a long time- secrete wax from glands on neck -- body wiping to wipe wax around
-May protect them from fungal infections that moist-skinned amphibians are prone to

Pelvic patch in toads

Bufo punctatus -ventral surface pouch of many amphibians - super permeable for lots of water intake
-sit with that part of body and take up water through that patch

Postural adjustments

when you're cold, you minimize surface are; when warm: get somewhere moist and make self littlest as possible to minimize surface area exposed to outside environment
-Rhinella marina, aestivation

Uricotelism

Uric acid secretion- minimize amount of water used when excreting nitrogenous waste
-Balance between energy spent producing nitrogenous waste and toxicity of waste;
Chiromantis

Ammonia

what fish produce-- high toxicity and solubility and water use but already in water; low energy use

Ureotelism

urea is slightly higher water usage and slightly more toxic;
Rana tigrina

Generalizations of Reptilian Integument

1. High Degree of keratinization
2. Generally lacking glands

2 kinds of Keratin

-Alpha keratin: more flexible
-Beta Keratin: stronger

Reptile Scales

-Thickening and keratinization is manifested in the form of scales
-->AKA plates, scutes, shields, laminae, lamellae, scansors, tubercles --depending on shape
-Epidermal scales are sandwich-like with an inner and outer generation (cross section of scale, they overlap)
-Prior to sloughing (ecdysis), a new generation forms beneath-- reduplication

Why does reptile skin have to be shed

so they can grow- their keratinized skin doesn't stretch-- new layer of skin produced underneath (reduplication)

Oberhautchen

pits and valleys- microornamentation on reptile scale
-Spinules, pits, laminae
-May modify scale color/reflectance

Reptilian Slough cycle

inner generation replaces outer generation; Stratum germativum- generates new material- kicks into gear during renewing phase
-Snakes: usually shed it all in one piece
-Lizards: pieces flake off
-Turtles: shed scutes

When snakes get ready to shed

the scales over their eyes get cloudy

Reptilian Epidermal Modifications

-Spines, "horns" true claws
-Scutes: large plate-like scales usually on ventral scales
-Rattlesnake Rattle
-Chin Tubercles
-Shovel tails
-Setae
-Fringe Scales
-Egg Teeth

True claws

two layers:
-unguis= hard part, encase finger bone on end
-subunguis
Sungazer (Cordylus giganteus)

Scutes in Turtles

Push up from bottom and make a pyramid- young on bottom, oldest in middle on top
-In some, (Chrysemys, Pseudemys) other scutes are periodically shed
-In others (Terrapene), scutes gradually wear away

Rattlesnake Rattle

Each segment with 3 little parts- these interconnect and are hollow; when they shake, the overlapping pieces vibrate against each other
-->shaker muscles in their tails
-when they shed, they produce another segment of their rattle
--If they eat more they shed more

Baby Rattlesnake

Birth Button: 1 rattle segment on end of tail- different in shape from the subsequent rattle segments
-Covered by rattle cap-- shed off shortly after hatching

Chin Tubercles in Nerodia rhombifera males

Species of water snake with thickened little knobs of keratin -- function is unknown... maybe tactile function when mating

Shield-tailed snakes (Rhinophis)

spend a lot of time burrowing;
Blunt, rounded tail with heavy microornamentaion --> picks up soil to form plug to block burrow entrance
-->dig with end of tail like a little shovel

Lizard Setae

toes with lamellae- folds of skin with little setae suction cups on them- made of branched suction cups;
-Geckos

Basiliscus Fringe Scales

Can walk on water!
-Can go pedal and run on back legs across water
-Helped by fringe scales that flip out on their back toes to provide more surface area to catch that water
--Foot plunging down makes pocket of air that provides enough force to be stepped

Egg teeth

a caruncle-- keratinized "tooth" in tuatara, turtles, and crocodylians (and birds);
Helps turtles get out of leathery shell; fall off after a couple of weeks

The reptilian dermis

Not as much going on as the amphibian dermis
-A few glands in some
-Bones often form in dermis
-Gastralia
-Plastron

Reptilian glands

-Musk Glands
-Femoral Glands
-Nuchal Glands

Reptile Musk Glands

crocodilians,
snakes,
lizards,
turtles
--> Phenylalkanoic acid by Kinosternids
Usually located near cloaca
-Stink Pot = Common Musk Turtle in MI --> Sternotherus odoratus

Reptile Femoral Glands

lizards - iguanids;
-Femoral pores lining inner thighs- glands mostly for producing pheromones for communication of sorts

Reptile Nuchal Glands

Keelbacks- Rhabdophis tigrinus;
Glands on backs of necks - specialize on toads- sequester toxins from toads
*Only poisonous snake*
--Arch neck / butt neck as a defensive behavior to express nuchal toxin glands
---Have some control- can mechanically break open poison glands by hitting predator etc.

Osteoderms

-bones within dermis
--Crocodilians, some lizards

Gastralia

Abdominal ribs- for protection; not connected to vertebrae (float);
Crocodile, tuatara

Plastron

Bottom part of turtle shell- derived from the dermis; Carapace = top part of shell, from flattened ribs

Pappochelys rosinae

Intermediate transitionary fossil between stem reptile and turtles-- probably pre-cursor to turtles
-->had flattened ribs, dermal bones that likely developed into carapace

Reptilian Osmoregulation Generalizations

-Reptiles show a significant reduction in cutaneous water loss
-Because of more efficient lungs, PULMONARY water loss is greater than in amphibians
-Lipid lamellar sheets are the most significant barrier to transcutaneous water flux

What is reduction in cutaneous water loss usually attributed to

generally attributed to epidermal scales
--BUT a scale-less snake (Pituophis melanoleucus) was discovered- has no greater water loss than it's scaled counterparts
-->there is probably some other mechanism acting here...

Reptile Respiration rate

higher than amphibians = lose water much more quickly through their lungs

If scales don't deter water loss, what does?

Lipid Lamellar Sheets: waxy sheets made of lipid layers- keep water in (cutaneous water movement not important for them so they can just keep it in);
--Landmann et al. have shown the most significant barrier to water loss -transcutaneous water flux- is the presence of these

Water loss in reptiles

-typically decreases with larger body sizes, both within and across species
-water loss varies depending on time spent on land vs. in water: More terrestrial reptiles lose less water and more aquatic reptiles lose more water

Adaptations for water conservation in reptiles

1. Uricotelism: uric acid production as primary nitrogenous waste
2. Turtles can enhance H2O reabsorption by active uptake of Na+ in the CLOACA
3.Breath-holding: greater extraction/breath, Hypercapnia tolerant (can hold a lot of CO2 in their blood)
4.Water Collection: behavioral and epidermal -- take advantage of any little water source in their environment; Thorny devil; adapt posture that sends water towards their mouths
5.Sodium Balance- extrarenal excretion via salt glands

Cloacal Drinking

Painted Turtles (Chrysemys picta) bask often with butts in water-- oxygen, salt, and water transported across cloaca

Thorny Devil (Moloch horridus)

Can take up water through channels in their skin via capillary action-- skin sucks up water;
-Drink morning dew forming on desert sand

Sodium Balance in reptiles

Reptiles are capable of living in saltwater (hypertonic medium) - most amphibians have not yet entered this niche;
-Saltwater means you end up being exposed to a lot of soidum- In the face of this "ionic load", some some tubular secxretions of Na+ occurs within the nephron (within the kidney)
-->Excess sodium can also make it's way to gland excreting extra salt --In many cases, dietary intake may be too much EXTRARENAL EXCRETION via salt glands

Salt glands in reptiles

-Lacrimal Glands: "crocodile tears", Diamond back Terrapins (estuary spp.), Sea Turtles
-Nasal Glands: marine iguanas sneeze it out
-Sublingual Glands: under tongue, sea snakes (Archordus, Hydrophiinae)
-Lingual Glands: mouth open to get rid of excess salt-- Crocodilians

Snake Glands

Some snakes have glands in various places on their faces with various functions for excreting various things

Basics of Cardiopulmonary system

-Heart: pumps blood
--Top of Heart= atria, RECEIVE blood from lungs (left atria via vena cava) or from body (right atria via pulmonary vein)
--Bottom = muscley ventricles- pump blood OUT
-Arteries: carry oxygenated blood AWAY from heart, tend to be able to withstand a lot of blood pressure
-Veins: carry deoxygenated blood TOWARD the heart, lower pressure, may have valves to prevent backflow

Human have two circuits through which blood goes

-Pulmonary circuit- pumps blood to lungs and back;
-Systemic circuit- pumps blood out to body and back

How do humans get oxygen?

Human lungs with alveoli-- sacs on ends of branches surrounded by capillaries --> through thin walls of capillaries is where gas exchange occurs
-Oxygen combines with hemoglobin and travels back

How do amphibian and reptile cardiopulmonary differ from humans?

Amphibians: cutaneous respiration- variation in how much they rely on lungs for repsiration
--Less chambers in heart (usually 3 chambers)
--Amphibians without lungs can get rid of left atria
Reptiles: even more variation, crocodiles with 4 chambered heart

Fish Cardiopulmonary system

2 chambered hearts-- can't separate oxygenated and deoxygenated blood, pulmonary and systemic circuits not really separated

Amphibian heart components

2 atria, 1 ventricle;
-Ventricle with lots of muscle-- works hard to pump blood out to rest of body
-Trabeculae: stingy connective tissue that cause heart to contract
-Conus Arteriosus: pouch responsible for diverting blood towards the PULMOCUTANEOUS artery toward systemic system
--Spiral Valve works in pouch to shift blood where it needs to go

Anura Heart Adaptations

-Fully divided atria -- interatrial septum is complete --> separate chambers
-Functionally divided ventricle
--Trabeculae and spiral valve separate systemic from pulmonary blood in conus arteriosus: spiral valve shoots unoxugenated blood to lungs or skin and oxygenated blood out to rest of body
--no cutaneous (systemic blood) return to left atrium

Anuran Heart Arches

Blood flow out of heart has arches-
-Systemic Arch: goes out and feeds rest of body
-Carotid Arch: comes up and feeds head
-Cutaneous arch: feeds skin

Differences within Anura Cardiopulmonary

Amphibians vary in their tendency to rely on cutaneous vs. aerial respiration
-Xenopus (African Clawed Frog): lungs very important (rely mostly on aerial respiration) = equal sized atria and large pulmonary artery
-Rana: skin very important = large RIGHT atrium and smaller pulmonary arteries

Terrestrial Caudates Cardiopulmonary system

-Skin MUCH more important
-Much smaller lungs --lungs absent in Plethodontids:
---No Spiral valve (no need to shunt blood either to lungs or to rest of body)
---No interarterial septum
---Heart chamber all have blood with same O2 concentration
---Get rid of one atria because no lungs involved; 2 chambers still because need to pump blood

Terrestrial caudate hearts are more similar to

the fish heart-- where systemic and gill circulation are all one thing

In amphibians, tissues of the _____ cavity can be important for respiration

Buccal;
-Plethodon glutinosus = 25%
-Rana temporaria = 0.9%
-Xenopus laevis = 0.2%

Aquatic Caudates Cardiopulmonary System

-Heavy reliance on EXTERNAL GILLS (Think Mudpuppy)
-Spiral valve capable of shunting blood to gills, minimizing blood to lungs
-Under certain conditions, lungs are important-- in drought, or when water becmoes anoxic, blood is shunted to lungs and flow to external gills is minimized

Reptilian Cardiopulmonary system

-No such thing as a "typical" reptilian heart
-- There's a lot of variation depending on the species- all tend to have 2 atria, but # of ventricles really depends
---Some with 2 very clear separate ventricle chambers
---Some with 3 but functionally 5- certain parts close off when heart contracts

2 Anatomical arrangements of the heart in extant reptiles

1. Crocodilian: interventricular septum (IVS) is VERTICAL-- 4 chambered heart (2 atria, 2 ventricles)
2. Non-Crocodilian (Squamates, Chelonians, Rhynchocephalians): Interventricular septum is HORIZONTAL & INCOMPLETE-- chambers not totally separate (complete separation only with pumping of heart); not ventricles, cavum dorsale and cavum pulmonale -- function like their own ventricles though

Crocodilian Heart

Right ventricle, Vertical IVS, left ventricle
(right to left);
-4 completely separate chambers (2 atria, 2 ventricles)
--May have systemic arch leaving from right ventricle- can pump de-oxygenated blood out to rest of body BYPASSING THE LUNGS
-->Space/ Connection from left systemic and right systemic arch (Foramin of Panizza)
-->Useful for when crocodilians stay underwater- hold breath and not use lungs: gives them more blood volume, also floods gut with extra blood, increasing CO2 in blood which is used to make bicarbonate for digesting bones

Non-Crocodilian Heart

Cavum dorsale, horizontal IVS, Cavum pulmonale (dorsal to ventral)

Further subdivision of Cavum pulmonale

-Cavum arteriosum
-Cavum venosum
*with cavum pulmonale, makes 3 chambers

Intracardiac Shunts

in crocodilian hearts; allows for the ability to move blood between pulmonary and systemic circuits
-Temporary, have to replenish at some point

Right to Left intracardiac shunts

Lungs are bypassed
-Portion of oxygen poor blood from the right atrium (would normally go to pulmonary artery) is EXPELLED THROUGH AORTIC ARCHES INTO SYSTEMIC CIRCUIT
-INCREASES volume of BLOOD GOING TO BODY & LOWERS its oxygen content
--Still have some residual oxygen in lungs, would be wasted if it was sent to lungs

Left to Right Intracardiac Shunt

Blood to lungs
-Oxygen-rich blood is diverted from the aortic arches into the pulmonary artery
-Increases the volume and oxygen content of blood going to the lungs
-Done when they need all that extra oxygen... death rolling with a buffalo for example

Structures involved in gas exchange in humans

Breath goes in nostrils, flows to trachea, past epiglottis ( covers the glottis aka opening of trachea)
-Trachea splits into 2 bronchi, then keeps on branching -- branches and pockets increase surface area -- capillary beds surround branches and this is where gas exchange occurs
-Diaphragm: sheet of muscle that drops for inhalation
-RIbs: intercostal muscles in between ribs help you to expand you rib cage

Amphibian Gas exchange

occurs across:
-Lungs (with less surface area than ours because not necessary with other places for gas exchange)
-Gills
-Skin
*Relative importance of these varies across taxa (and varies at different stages of their life)

Amphibians Gills

-Maximum of THRE PAIRS found in larval and neotenic (=paedomorphic) forms
--Larvae: tadpoles!
--Neotenic: adults that stay like larvae-- like mudpuppies, axolotl (retain larval form into adulthood)
-May be external or in a branchial chamber
--External = gills like axolotl, salamander larvae
--Branchial Chamber: communicates with aquatic medium via a spiracle and the mouth -->water goes in through mouth, then exits through holes (spiracles)
--Like tadpoles