Snake Lecture Flashcards
What is the size, lifestyle, diet, reproductive mode, and other characteristics of Typhlopidae?
Size – few cm to about 1m
All oviparous
Egg retention common; freshly laid eggs may contain advanced embryos
Rhamphotyphlops braminus -triplod parthenogen; product of interspecific hybridization, parthenogenesis has allowed widespread dispersal
Probably native to so pacific region
Established on oceanic islands (Hawaii, Madagascar)
Diet – ants or termite pupae, larvae, eggs and adults
Gorge themselves inside ant or termite nests, individuals have over 1500 food items in gut (from esphoagus to cloaca)
1 species from New Guinea specializes on earthworms
Fossorial live underground no need for well developed eyes
What is the scientific name for blind snakes?
Typhlopidae
What is the size, lifestyle, diet, reproductive mode, and other characteristics of Leptotyphlopidae?
Smaller in size than Typhlopidae (less than 10 cm, some up to 30cm)
All oviparous
Females tend to eggs
Observed in Eastern Screech-owl nest high in trees
Diet – soft-bodied arthropods (Ants, ant larvae and pupae, termites, and other insects)
What is the family of slender blind snakes and thread snakes?
Leptotyphlopidae
What is the size, lifestyle, diet, reproductive mode, and other characteristics of Boidae?
Size- less than 50cm to over 9m
Habitat – rainforest, dry tropical forests, sandy and rocky deserts and temperate coniferous forrests
Habits – terrestrial, Arboreal, aquatic, semi-fossorial
Diet – Extremely varied
Larger species – variety of vertebrates (mammals, reptiles)
Specialist of frogs and salamanders – Exiliboa placata (Southern Mexico)
Infrared-sensitive pits – variable in presence, position (upper, lower and between labial scales. Rostrum scales) and #, absent in Erycinae
Oviparous (All pythoninae) and viviparous (all Boidae and Erycinae)
Many Phytons – construct nests of leaves or lay eggs in burrows
Females of some pythons – coil around clutch and generate heat through muscular contraction
Up to 100 eggs laid by larger pythons
Anacondas (Enectes spp) – inhabit aquatic environments (rivers, ponds, flooded savanna’s)
Diet – fish, amphibians, turtles, caimans, birds, pacas, capybaras, deer
Ambush predators
What is the size, lifestyle, diet, reproductive mode, and other characteristics of Viperidae?
Terrestrial or arboreal
Habitat – rainforest to deserts to high mountains
Oviparous or viviparous
Females of some species remain with eggs of young for sometime
Diet variable – some juveniles of large vipers feed on lizards and amphibians; adults feed on mammals
Agkistrodon piscivoris (eastern cottonmouth) – even feed on …
Low to high elevation
European Viper (Vipera berus w/ Arctic circle, Europe )
Rattlesnakes (Crotalus Sistrurus) – tip of tail modified into rattle composed of interlocking segments of Keratin. Produces sound – anti-predator defense
Largest new world crotalinae (3.5m) 3 species of bushmasters ()
Viperinae – lack pit organs
Largest Viperinae 1.5 -1.7m
Most viperines less than 1m
What is the size, lifestyle, diet, reproductive mode, and other characteristics of elepidae?
All venomous
Most oviparous some viviparous
Habits- terrestrial (cobras, kraits, coral snakes), arboral (mambas), aquatic, semi-fossorial, or marine (Sea snakes)
Habitat- arid deserts to tropical rainforests
Diet extremely variable and reflect habitat and lifestyle
Aquatic elapis – primarily fish
Kind cobras – primarily other snakes
New world coral snakes – elongate vertebrates (Amphisbaenians, other snakes, and eels)
Other elapids – frogs, toads, lizards, reptile eggs, rodents and birds
Sea snakes – fish, fish eggs, crustaceans, cuttlefish
Size less than 50cm to 5m
Most terrestrial elapids – oviparous, some viviparous
King cobras and African forest cobra – construct nest of leaves and decaying vegetation for egg laying
Known for hood-spreading defensive displays – cobras, mambas
Hood formed by spreading elongate ribs in neck region
Spitting cobras
Mimicry – New worlds snakes (Micrurus and Leptomicrus) Mimicked by non-venomous species (Pliocercus, Lampropeltis, Erythrolampus)
Seas snakes- Special adaptation to coastal marine and estuarine waters
Salt glands- Also ability to rehydrate through rainfall
Most sea snake – viviparous; give birth to young in water
Body laterally compressed
Ventral scales much reduced
Nostrils closed by valves
2 seas snake species
Likely entered lakes when connected to sea
What is the size, lifestyle, diet, reproductive mode, and other characteristics of Colubridae?
Huge Family – 63% of all snakes over 1,800 species
No unique characteristics
Several species are venomous
Characteristics of Crocdilians (Crocodylia)
Distribution – throughout tropical and subtropical regions
Alligators found in warm temperate regions of U.S. and China
Most freshwater, some enter brackish or saltwater
Elongate bodies with long snouts and powerful limbs and tail
Heavily armored – plated of bones with in dermis underneath epidermal scales (Osteoderms)
Teeth – Thecodont like mammals, set in sockets and attached by ligaments
Limbs short and fully webbed
Aquatic, nitatating membrane
Morphological apdaptions for breathing in aquatic environment
Allow crocodilians to breath underwater while holding prey in mouth
Muscular partition between pectoral and abdominal cavities (comparable to diaphragm)
Well-developed alveoli in lungs associated with respiratory efficiency
Interventricular septum; however, mixing of blood occurs via aperture
Nostrils located dorsal on tip of snout; closed by valves when diving
Well-developed secondary palate separates buccal and respiratory passages
Nasal passages open internally in throat behind secondary palate; can be closed off from throat by fleshy fold on back of tongue and palate
Dome pressure receptors – sensory organ along dorsal and ventral surface of head
Organs are able to detect surface waves at air-water interface; from prey, predator or raindrops
Postcranial dorsal and ventral scutes (Crocodylids and Gauialids) may function in osmoregulation
Glands on gular and cloacal regions – possible produce pheromones for mating/nesting
Exceptional swimmers; can move fast on land
Walking – belly held high off ground and limbs placed underneath body
Also, belly crawl when plunging into water
In water, fold limbs against body and use lateral undulations of body and tail to swim
All oviparous
Wither lay eggs in mound nests constructed from vegetation and soil or lay eggs in soil
Temperature – dependent sex determination
Parents guard nest; some species break open nest; carry nestling in mouth and remain with them for weeks/months
Extensive parental care unique to group
Hearing good, eye sight, and smell excellent
Vocalizations complex
Territorial bellowing
Aggressive warning towards intruders
Neonates vocalize to synchronize hatching, elicit nest-opening behavior by attending adults; maintain group cohesiveness and alter adults to potential threats
Diet- Larger crocodilians (Fishes, turtles, birds, mammals, and shellfish
Diet- smaller crocodilians (insects and frogs)
Food located by smell; gular pumping brings olfactory stimuli to nasal chamber
Predation – general nocturnal
Downing used to subdue large prey
Do not Chew; dismantle prey into size suitable for shallowing
many species exploited worldwide for hide and meat
American alligator – heavily exploited during the 1700s to near extinction
Carmen niger and crocodiles mindorenis – vastly reduced ranges due to hunting
Alligator and crocodile farming – successful commercial venture for hide and food in many countries
What is the size, lifestyle, diet, reproductive mode, and other characteristics of Alligatoridae (Alligators and Caimans) ?
Teeth of the lower jaw – fits into pits in upper jaw and not visible
Size – 1.7m to 6m
Habitat – large rivers, lakes , swamps and lagoons
Exception – Paleosuchus inhabits small streams and pools in forested areas; alligators better costal marine waters
Alligator mississippiensis – only crocodilian to inhabit temperate areas where water freezes
Radiotelemetry studies – more into shallow water and position themselves with nostril above surface ice
Drawf caimans – inhabit forested areas with little sun to incubate eggs
Nest constructed next to termite mounds, metabolic heat generated from mounds is primary source for egg incubation
What is the size, lifestyle, diet, reproductive mode, and other characteristics of Crocodylidae (Crocodiles) ?
Crocodylids– 4th tooth of lower jaw is visible
Size 2m to 7m
Osteulaemus – inhabits small streams in rainforest and Savannah (Similar to Paleosuchus)
Construct burrow under riverbanks; lay eggs in mound nest
Characteristics of Snakes
Cosmopolitan; high latitudes (above arctic circle and Europe) and high altitudes (above timberline in Himalayas and Andes) on all continents except Antarctica
63% are colubrids
Derived character – reduced limbs and girdles
Left lung reduced
Tail breakage – intervertebral (pseudoautotomy)
Scleral ossicles – bones dermal plates supporting eye - absent
Transparent spectacle covering eye
Greater than 120 pre-cloacal vertebrae
Ciliary body of eye lacks muscles – eye accommodates by muscles of iris which move the lens
Left sytemic(arterial) arch larger than right – opposite of tetrapods
Skull highly kinetic
Oviparous or viviparous
Genetic sex determination only
Sexual dimorphism rare – lack species specific structures or sexual/territorial displays
Males generally have longer tails, many have keels on Supra-anal scales or tubercles on chin
Species retaining pelvic elements – larger in males and used to stimulate females during copulation
Sexual dimorphism rare
Teeth – long, slender and slightly curved
Modified Pleurodont…
Teeth – either homodont (most) or heterodont (colubrids)
Colubrids – individual teeth modified as grooved or hollow finds
# of the etch variable with in closely related genera
4 general categories of dentition
Aglyph - Homodont maxillary dentition (Colubrids)
Opisthoglyph – Posterior teeth enlarged (Rear-fanged – colubrids)
Proteroglyph – Anterior teeth enlarged and hollow (elepids); maxilla enlarged; fang not erected
Solenoglyph – Anterior teeth enlarged and hollow (viperids); maxilla short; fang erected by rotation of maxilla
Venom
Venom glands associated with fangs
Complex cocktail of proteins, including enzymes and other molecules
Difficult to treat snakebites
Function – subdue prey
3 general categories of venom
Hemorrhagins – destroy blood vessel linings or hemolysins (destroy red blood cells) - vipers
Myotoxins – destroy skeletal muscles
Neurotoxins – act at synaptic or neuromuscular junctions - elapids
Some exceptions to general patterns
Venom – arisen evolutionarily from digestive enzymes
Sense- smell and eyesight well developed
Lack external and middle ears
Pick up airborne and substrate-borne “sounds”
Smell – used extensively in foraging and interspecific communication
Pheromones – important in reproductive ecology; produced in the skin and from scent glands in tail
Visual cues – essential in foraging and defense
Exception – burrowing species with reduced eyesight
Pit organ – infrared receptors – pick up heat
Boidae – upper and lower labial scute with multiple pits
Crotalinae – single pit present between eye and nostril
Pit organ
