Herpetology Quiz #2

What does the order Crocodylia contain?

Crocodiles, Alligators, Gharials, & Caimans

Is Crocodylia paraphyletic or monophyletic?

Monophyletic

Who are Crocodylia closely related to?

Birds (Aves)

Who did Crocodylia descend from?

Pseudosuchians

Conservation concerns for Crocodylia

1. Habitat destruction
2. Hunting
3. Pollution
4. Floods/drought (hydrology)
5. Dams
6. Temperature change (temperature sex-dependent)
7. Poor protection

Biology of Crocodylia

• - Found in Asia, Africa, & USA
  - Largest living reptiles

• - Mostly aquatic: wetlands, rivers, oceans, lakes

• - Crocodile Sizes:

• Largest: Saltwater Crocodile

• Smallest: Dwarf Caiman

Crocodylia Skin

• - Dry & impermeable

• - Scutes

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• Osteoderms over the neck, trunk, & tail

• Osteoderms fuse with dorsal skull

Crocodylia glands

• - Mandibular (gular) glands:

• Secretes lipids

• Used for communication & pheromones

  
  

• - Cloacal glands:

• “musk”

• Used for communication & pheromones

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• - Glands likely used for mating & nesting

• - Salt glands remove excess salt & are located in the tongue

Do Crocodilians shed (ecdysis)?

• - Yes, they shed in patches & small sheets similar to how a turtle (Testudines) shed

Crocodylia teeth

• - 60-70 teeth at once

• - Thecodont teeth → attach to bone by sitting in sockets

• - Cone-shaped, designed to grab & hold prey

• - Teeth can be replaced throughout life

Crocodylia Digestive System features

• - Teeth

• - Stomach

• - Small & large intestine

• - Cloaca

• - Liver

• - Gallbladder

• - Pancreas

• - Secondary palate → separates nasal passage from mouth, allows for respiration while food is still in the mouth

Crocodylia Reproductive Structures

• Male Reproductive Structure: Testes & single penis

  • Female Reproductive Structure: Ovaries, oviducts, cloaca, temperature-dependent sex determination (TSD)

Crocodylia Skeletal System

• - Diapsid skull

• - No collar bone

• - Vertebrae (atlas & axis)

• - Pelvic & pectoral girdles

Crocodylia Nervous System

• - Mechanoreceptors in skin

• - Outer, middle, & inner ear

• - Muscles that close ear cavity → prevents injury

• - Well-developed eyes (see UV & color)

• - WIthout parietal eye or Jacobson’s Organ

Families of Crocodilians

• - Crocodylidae (in USA)

• - Gavialidae

• - Alligatoridae (in USA)

Physical traits of Crocodylidae

• - 2.5-7 m long

• - Long, broad, pointed jaws

• - Fourth lower mandibular tooth outside of mouth when closed (“snaggle tooth”)

• - Claw, webbed toes

• - Short legs, long muscular tails

Biological traits of Crocodylidae

• - Found in Africa, Asia, Australia, USA

• - Aquatic:

• In marshes, mangroves, tidal areas, rainforest streams

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• - Build mounds for nests (female guards the nest)

• - 15 years till maturity

• - Vocalizations

• - Brumate → state of inactivity & torpor

• - Survive months without food or water

Crocodylidae Species in USA: American Crocodile, Genus & Species

• - Genus: Crocodylus

• - Species: Crocodylus acutus

• Physical traits of Crocodylus acutus (American Crocodile)

• - 0.3-0.4 m as adults

• - Gray/green color, can have gray or brown bands down tail

• - Sides have gray-black spots

• - Pointed snouts

• Biological traits of Crocodylus acutus (American Crocodile)

• - Located in Florida, Central & South America, Islands

• - Eat fish, crabs, turtles, snakes, small mammals

• - Secretive, costal, brackish, & saltwater habitats

• - Endangered:

• Habitat loss, degraded hydrology, salinity changes, human hunting

Gavialidae Physical traits

• - Long, slender snout

• - Narrow jaws with sharp teeth

• - Males have a ghara at the end of their nose

Ghara (used for vocal communication & attracting mates)

Gavialidae Biological traits

• - Located in Asia

• - Highly aquatic → rarely moves from water:

• Fast-flowing, deep waters

• Adults congregate

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• - 15-18 years maturity

• - Hole nesting (female guards the nest)

• - Eat fish & frogs

• - Critically endangered

Alligatoridae Physical traits

• - 2-4 m long

• - Dark green colored, can have lighter stripes down the body

• - Large, rounded snout

• - 4th lower mandibular tooth typically inside mouth

• - Webbed feet & claws

Alligatoridae Biological traits

• - Found in USA & China

• - Aquatic:
  Freshwater, coastal, swamp, dunes, lakes, rivers, wetlands

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• - Eat fish, mammals, mussels, birds, etc

• - Burrow

• - Mount nesting (female guards the nest)

• - 8-15 years maturity

• - Vocalizations

• - Can withstand freezing waters:

• Brumate underwater

• - Nostrils are above water for breathing

• - Water freezes around nostrils

• - Alligatoridae emerges from water & moves on warmer days

Physical traits of Species in USA: American Alligator

Crocodylidae Species in USA: Alligator mississippiensis (American Alligator), Genus & Species

• - Genus: Alligator

• - Species: Alligator mississippiensis

Physical traits of Alligator mississippiensis (American Alligator)

• - 2-3.5 m long

• - Dark green colored, can have stripping (prominent when young)

• - Rounded snouts

Biological traits of Alligator mississippiensis (American Alligator)

• - Located in Southern/Southeastern USA

• - Freshwater, slow-moving rivers, lakes, swamps

• - Previously near extension:

• Illegal poaching for alligator productus, habitat loss

Major Amphibian Characteristics

• - Vertebrates

• - Ectotherms

• - Tetrapods

• - Unshelled eggs (non-amniotic)

• - 3-chambered heart

• - Larval offspring stage (in many)

• - Permeable skin (NO scales/scutes)

• - Lungs & more

Larval offspring stage in Amphibians

• - Paedomorphic species → sexually mature while retaining features of the larval stage (e.g., adult salamanders retaining gills)

Anura Skin

• - Moist, permeable, requires external water (granular & mucous glands)

Do Anuras shed (ecdysis)?

• - Yes, adults shed cyclically (every few days or weeks)

• - Skin is not keratinized like in reptiles

• - Epidermal cells mature & are pushed to the surface

Anura Digestive System

• - Teeth

• - Tongues

• - Stomach

• - Small & large intestine

• - Cloaca

• - Liver

• - Gallbladder

• - Pancreas → short intestinal tract

Anura Reproductive Structures

• - Primarily external fertilization

• Male Reproductive Structures: cloaca, testes, no external copulatory organ

• Female Reproductive Structures: cloaca, ovaries, oviduct

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• - Tailed frogs are the exception: internal fertilization, males have external copulatory organ (Family Ascaphidae), everted extension of cloaca

Difference between Crocodylian & Anura Skeletal System

Crocodylian: Diapsid skull, no collar bone (clavicle), no saltatory movement

Anura: Anapsid skull, lacks ribs, saltatory movement

Anura Nervous System

• - Lateral line in larvae & some adults:

• Detect movement in water

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• - Mechanoreceptors in lines down the body

• - Ears:

• Lack external ear structures, many lack tympana (eardrum)

• Have middle & inner ears

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• - Eyes:

• see color & UV, 2 types of rods: Green rods → unique to amphibians

• have a parietal eye & large Jacobson’s Organ

Anura International Family: Centrolenidae - Glass Frogs

• - Kéntron = point or spur

• - Ōlénē = elbow, forearm

Centrolenidae - Glass Frogs Physical traits

• - 22-35 mm SVL typically as adults

• - Some species have ventral transparent skin → internal organs are visible, Greenish colored skin on dorsal side

• - Skin turns red in oxygen-poor environments, blood flows near skin

• - Males can spine on the front of the upper arm (humerus)

Centrolenidae - Glass Frogs Biological traits

• - Located in Northern & Southern America

• - Found near streams & rivers, in trees & vegetation (i.e., evergreen, deciduous rainforest, cloud forests

• - Nocturnal

• - Oviparous (20-30 eggs)

• Lay eggs on vegetation over water

• When eggs hatch, tadpoles fall into water & live in leaf packs & muddy substrates

• - Male guards egg clutches

Anura International Family: Dendrobatidae - Poison Frogs

• - Dendron = tree

• - Bátēs = tree climber

• Can be semi-arboreal frogs

Dendrobatidae - Poison Frogs Physical traits

• - 13-55 SVL in adults

• - Skin contains poison:

• Batrachotoxins - one of the most toxic substances produced by animals

• - Many are bright colored

• Aposematic coloration - bright coloration as a warning of danger to predators

• Can be orange, green, red, yellow, gray, black, brown

What is the difference in poison & venom?

• - Poison: ingested by attacker, organism doesn’t typically have a way to inject toxin

• - Venom: injected into prey/attacker, organism has structure (ex. fangs) to inject toxins

Dendrobatidae - Poison Frogs Biological traits

• - Located in Nicaragua to Northern & Central, South America

• - Riparian, terrestrial, or semi-arboreal

• - Oviparous, ~9 eggs per clutch

• - Males typically attend to the nest:

• Eggs in leaf litter, along streams, or in arboreal retreats

• Tadpole wiggle onto the male’s back & transported to water

• Some parents feed the tadpoles

Anura National Family: Ascaphidae - Tailed Frogs

• - Askaphos = spade, shovel → lack “spade” on feet, found in some frogs

Ascaphidae - Tailed Frogs Physical traits

• - 25-55 SVL as adults

• - Males have external sex organs

• - Cloaca is everted for internal fertilization

• - Have a “tail”, supported by cartilage

• - Tadpoles have large, sucker-like mouths

Ascaphidae - Tailed Frogs Biological traits

• - Located in Pacific Northwest & Rocky Mountains

• - Found in clear, cold, fast-moving streams

• - Fertilization takes place underwater

• - “Tail” prevents sperm from floating downstream

• - Eggs are laid in moist, terrestrial substrate

• 44-70 eggs are laid

• - Males attend to the nest and move tadpoles to water (moves tadpoles on their backs)

• - Tadpoles take ~4 (up to 7) years to metamorphose

Ohio Families: Bufonidae - True Toads & Harlequin Toads

• - Bufo = toad

Bufonidae - True Toads & Harlequin Toads Physical traits

• - Varies in size, <20 mm SVL

• - Have a Bidder’s Organ (undeveloped ovary near the testes

• In male tadpoles & some adults

• Regulates hormones, could produce eggs

• - Many have thick, warty/bumpy skin

• - Toothless

• - Many have parotid glands (poison glands)

• - Some are highly toxic & aposematic coloration (bright coloration for warning predators)

Bufonidae - True Toads & Harlequin Toads: Biological traits

• - Most are terrestrial & less reliant on water than many other frogs

• - Explosive reproduction: any/first warm, rainy evening they emerge & reproduce

Variety of reproduction in Bufonidae: - True Toads & Harlequin Toads

• - Lay eggs in strings (similar to Leptotyphlopidae (Thread snakes)), tadpoles develop in weeks

• - Terrestrial eggs, direct development without tadpoles

• - Viviparity

Bufonidae - True Toads & Harlequin Toads Concerns

• - Eat almost anything

• - Breed most of the year: lay 8,000-30,000 eggs at once

• - Use urban agriculture, natural habitats

• - Out-compete natives

• - Native predators won’t eat them or they will die when they do (Bufonidae are toxic)

Anura species in Ohio: Anaxyrus americanus (American Toad)

• - Genus: Anaxyrus

• - Species: Anaxyrus americanus