Reptiles 1 Flashcards
reptiles taxonomy, number of species
- what are the 4 orders
- 4 orders:
- Squamata – snakes and lizards
- Testudines (chelonians) – turtles
- Crocodylia
- Rhynchocephalia – tuatara
<><> - > 11,000 species
<><><><> - Reptiles are the animals in the class Reptilia, a paraphyletic grouping comprising all sauropsid (“lizard faces”) amniotes except Aves (birds). Living reptiles comprise squamates (snakes and lizards), turtles, crocodilians, and rhynchocephalians (Sphenodontia, tuatara).
- Toxicofera = “those who bear toxins“; it encompasses all venomous reptile species, as well as numerous related non-venomous species.
- As of October 2023, the Reptile Database includes about 92 families, 1253 genera, and 12,060 species.
common types of lizards we may see
- Agamids (f) – bearded dragon, Chinese water dragon, Uromastyx
- Chameleons (f)
- Iguanas(f)
- Geckos (sf)
- Skinks(sf)
- Tegus(sf)
- Varanids (monitors)(f)
f= family
common types of snakes we may see
- Pythons (sf)
- Boas (sf)
- Colubrids (sf)
- Elapids (sf)
- Vipers (f)
sf = subfamily
f = family
<><><><>
* Pythons – non-venomous, oviparous
* Boas – non-venomous, ovo-viviparous, vestigial pelvic girdle (spurs)
* Colubrids – generally non-venomous, can be rear-fanged
* Elapids – venomous, permanently erect fangs
* Viperids – venomous, hinged fangs
what are testudines
- Hidden neck (so)
> Tortoises
> Turtles - Side neck (so)
<><> - so = suborder
reptile metabolism
- speed
- anaerobic vs aerobic
- Slow metabolism:
- 1/5-1/7 mammalian metabolism
- Vary with species and metabolic state
<><><> - Anaerobic metabolism:
- Switch to anaerobiosis with vigorous activities
- Increased lactate production
what does it mean that reptiles are Ectothermic and poikilothermic
- pros and cons
- Pros: do not waste energy for thermogenesis
- Cons: all activities are limited by ambient temperature, limited aerobic capacity, brumation
- Preferred optimum temperature zone (POTZ)
<><><><> - Ectotherm (vs. endotherm) = an animal that is dependent on external sources of body heat.
- Poikilotherm (vs. homeotherm) = an animal that cannot regulate its body temperature except by behavioral means such as basking or burrowing.
- Brumation = a lethargic state that some ectothermic animals, such as many reptiles, assume during cold conditions. Partly analogous to hibernation, but physiological differences include that brumation does not depend on stored fat, but rather on reduced metabolic activity.
reptile integument
- what type
- shedding
- some lizards and crocodiles are…
- chelonians?
- chromatophores?
- Most reptiles have scales
<><> - Shed periodically = ecdysis
> Snakes: periodically in one piece
> Lizards: periodically in pieces
> Turtles and crocodilians: continuously in small pieces
<><> - Osteoderms in some lizards and crocodilians
<><> - Chelonian shell:
- Fused ribs, vertebrae, and some osteoderms
> Carapace, plastron, bridges - Covered by epidermal scutes
<><> - Chromatophores: colour change in some
reptiles musculoskeletal
- snake skull type?
- pectoral?
- regeneration?
- growth?
- Prokinetic skull
- Highly kinetic skull in snakes
- Pectoral girdle is different
- Autotomy and tail regenerationin
lizards - Some species keep growing all their life
<><><><> - Autotomy = “self-amputation”. Often, loss of the tail as a defensive strategy. It is created by a vertical fracture plane, containing no bone, passing through the body and part of the neural arch of each caudal vertebra. It occurs in many lizards, such as the iguana, skink, and gecko species, where the tail is not essential for survival. Species like chameleons and monitors, which rely on their tails for climbing and defense, do not shed their tails. Similarly, the marine iguana, which relies on its large rudder tail for swimming in the sea, lacks fracture planes.
Coelomic Cavities of chelonians
- Pleural cavity and peritoneal cavity
- Separated by post-pulmonary septum
Coelomic Cavities of squamates
- Single pleuroperitoneal cavity in most, except:
- Monitors have a post-pulmonary septum
- Tegus have a post-hepatic septum
Coelomic Cavities of crocodilians
- Like birds (without the air sacs)
Generalities on Internal Anatomy
- fat
No subcutaneous fat
* Fat bodies in caudal coelom
* Fat stored in tail of leopard gecko
organ placement in snakes, generally
- are right or left more cranial
Elongated anatomy in snakes
* Right organs are more cranial than left
categories of reptile dental anatomy
- Acrodont
- Pleurodont
- Thecodont
- Beak
- Snakes have 6 rows of teeth
what is acrodont? who has this? prone to what?
- Agamids, chameleons
- Teeth are not replaced
- Direct attachment to jaw bones
- More prone to periodontal disease
what is pleurodont? who has this?
- Iguanids and snakes
- Teeth replaced
- Direct attachment to jaw bones on one side
who is thecodont?
- Crocodilians and some snakes
> more like what we are used to in ourselves
what reptiles have a beak?
chelonians
snake teeth orientation? venomous ones have what?
Snakes have 6 rows of teeth
* Venomous snakes have venom-delivering teeth (fangs)
* (Proteroglyphous vs opisthoglyphous vs solenoglyphous)
<><><><>
* In most snakes, teeth are located on the dentary of the lower jaw, the maxilla, the palatine bone, and the lateral pterygoid plate. The latter form an “inner row” of teeth that can move separately from the rest of the jaws and are used to help “walk” the jaws over prey. Several snake lineages have evolved venom which is typically delivered by specialized teeth called fangs located on the maxilla.
* Most snakes can be placed into one of four groups, based on their teeth, which correlate strongly with venom and lineage:
* Aglyphous snakes (“lacking grooves”) have no specialized teeth. Most aglyphous snakes are non-venomous. All snakes have aglyphous teeth, i.e., teeth that aren’t considered fangs.
* Opisthoglyphous (“rearward grooves”) snakes possess venom injected by a pair of enlarged teeth at the back of the maxillae, which normally angle backward and are grooved to channel venom into the puncture. Called “rear-fanged”. Example = colubrids.
* Proteroglyphous snakes (“forward grooved”) have shortened maxillae bearing few teeth except for a substantially enlarged fang pointing downwards and completely folded around the venom channel, forming a hollow needle. Because the fangs are only a fraction of an inch long in even the largest species these snakes must hang on, at least momentarily, as they inject their venom. Example = elapids.
* Solenoglyphous snakes (“pipe grooved”) have the most advanced venom delivery method of any snake. Each maxilla is reduced to a nub supporting a single hollow fang tooth. The fangs, which can be as long as half the length of the head, are folded against the roof of the mouth, pointing posteriorly. The skull has a series of interacting elements that ensure that the fangs rotate into a biting position when the jaws open. Solenoglyphous snakes open their mouths almost 180 degrees, and the fangs swing into a position to allow them to penetrate deep into the prey. While solenoglyph venom is typically less toxic than that of proteroglyphs, this system allows them to deeply inject large quantities of venom. Unique to vipers.
Gastrointestinal System for reptiles depends on…
- how do they differ?
Depends on the diet:
* Herbivores: long GIT, 1 cecum, large colon
> Iguana, terrestrial chelonians
* Carnivores: Short GIT
> Varanids, snakes (very distensible stomach)
venomous gland are where in
- Viperids, elapids
- Colubrids
- Helodermatid lizards, e.g., Gila monster
Venomous glands
* Viperids, elapids: temporal region
* Colubrids: Duvernoy’s gland
* Helodermatid lizards, e.g., Gila monster: along the lower jaw
<><><>
* Duvernoy’s gland is a gland found in some groups of colubrid snakes. It is positioned posterior to the eye, encased in a thin cover of connective tissue, and consists mostly of serous cells. A single, short duct extends anteromedially from the lumen of the gland to the base of the posterior fangs. Function?
reptile tongue types
- Forked in snakes and some lizards
- Projectile and prehensile in chameleon
reptile butt is similar to what other animals
- Cloaca similar to birds
how does metabolism of digesting snake change?
Metabolism of digesting snakes may increase by 7-10 times
