Vertebrates Lecture Flashcards
Class Chondrichthyes (Sharks)
To immobilize a shark, one can punch it in the nose or use a magnet (sharks don't like magnets).
Class Osteichthyes (Bony Fishes)
Subphylum Vertebrata: Animals with a vertebrae.
Two groups:
Ray-finned fish (99.9% of fish).
Lobe-finned fish (coelacanth and lungfish).
Coelacanths were thought to be extinct but were rediscovered about 50 years ago.
Ray-finned Fish
Fins have bones that radiate outwards, covered by thin skin.
Fins are used for balancing and steering underwater.
Most have a swim bladder or gas bladder containing nitrogen gas for buoyancy.
Have an operculum (covering over the gills) to draw water into the gills, allowing them to breathe without constant swimming.
Lobe-finned Fish
Bones in fins resemble bones of land animals.
Fins are more for walking or crawling.
Includes coelacanths and lungfish.
Swim Bladder Disease
Disease found in aquarium fish. May be due to infection or overeating.
Interferes with swim bladder function, causing the fish to flip over.
Feeding green peas is suggested as a remedy.
Swim Bladders as Valuable Commodity
The swim bladder of certain fish in the Gulf of Mexico/California is highly prized in Asia (up to $10,000).
Illegal fishing due to declining populations.
Example case: Man drying 214 swim bladders worth $3.6 million.
Negative consequences: Nets catch unwanted animals like porpoises.
Lobe Fin Fish Details
Scientists believe they are the direct ancestors of animals that moved onto land.
Ancestors of tetrapods (four-limbed animals).
First land animals likely resembled amphibians.
Fish Respiration
Gills and Capillaries
Fish breathe through gills; gas exchange occurs in capillaries.
Countercurrent flow of blood and water maximizes oxygen diffusion into the capillaries.
In countercurrent flow, blood and water flow in opposite directions, ensuring efficient gas exchange.
Shark Respiration
Sharks swim to pass water through their gills.
Tetrapods
Animals that move on land evolve feet with digits, ears for airborne sounds, and lungs.
Early land animals (amphibians) have both lungs and gills.
Class Amphibia
Includes frogs, toads, salamanders, and caecilians.
The word "amphibian" means "two lives" (aquatic tadpole stage and terrestrial adult stage).
Ectothermic (cold-blooded).
Amphibians have both lungs and gills.
Tadpoles have gills. Adults have lungs.
Many amphibians breathe through their skin.
Sensitivity to Pollution
Amphibians are susceptible to water pollution due to skin breathing and can serve as pollution detectors.
Insecticides and agricultural chemicals may mimic hormones, causing abnormal limb development.
Amniotic vs Non-Amniotic Eggs
Amphibians do not lay amniotic eggs (shelled eggs with an amnion).
Amphibian eggs have a jelly-like protective layer (not an amnion) that may prevent drying out and protect from predation.
Orders of Amphibians
Urodela (Caudata): Newts and salamanders.
Anura: Frogs and toads.
Apoda: Caecilians.
Order Urodela (Caudata)
Contains newts and salamanders, mostly found in North America.
Adults and young have tails.
Newts arms tend to be angled, salamanders' arms tend to be at a right angle.
Toxic Newts
Taricha granulosa exudes a poison (tetrodotoxin), like puffer fish.
Order Anura
Frogs and toads that do not have tails in their adult forms.
Frogs tend to have colorful, smooth skin and legs for jumping.
Toads tend to have brownish, bumpy skin and hop rather than jump.
Frogs have teeth-like ridges in their upper jaw.
Frogs are found near water, while toads can be found away from water.
Frog eggs are laid in clusters; toad eggs are laid in long chains.
Poison Dart Frogs
Used by native people in the Amazon for hunting by dipping arrows in their skin.
Toxins are derived from their diet (possibly beetles).
Native people use trace amounts of poison for spiritual rituals, though it can be fatal.
Surinam Toad
Eggs merge into the female's skin and develop into tadpoles until they emerge.
Transparent Frog
Species with transparent underside, showing its organs.
Order Apoda
Contains caecilians, which look like a cross between snakes and earthworms.
They do not have limbs and have tentacles for smelling or sensory purposes.
They have small, non-functional eyes and live underground.
They use internal fertilization (males inject sperm into females).
Some species of mother thicken their skin for scraping off the skin by young for food.
Amniotes
Reptiles, birds, and mammals are amniotes.
Amniotic eggs have an amnion layer with amniotic fluid surrounding the embryo.
Amniotes also have an allantois and chorion.
Amnion Structures
Amnion: Contains amniotic fluid to cushion the embryo.
Allantois: Used in respiration and waste excretion.
Chorion: Gives rise to the placenta for nutrient and waste exchange.
Most amniotes lay shelled eggs and have thick skin to prevent water loss.
They have rib cages for respiration and well-developed kidneys and large intestines for water retention.
Class Reptilia
Includes tuatara, lizards, snakes, turtles, crocodiles, and dinosaurs. Have waterproof skin and lay shelled eggs.
Ectothermic.
Very efficient at converting food into energy.
Have a closed circulatory system.
Amphibians and Reptiles have a three-chambered heart.
Two atria and one ventricle.
Crocodile Evolved Hearts Structure
Crocodiles are considered the most evolved reptiles. Although technically they have a three-chambered heart, their hearts begin to show two ventricles.
Reptile's Kidney and Urine
Reptiles cannot produce concentrated waste because their kidneys lack a Loop of Henle to reabsorb water.
Orders of Reptilians
Crocodilia: Crocodiles, alligators, and caimans.
Sphenodontia: Tuatara.
Squamata: Lizards, snakes, and skinks.
Testudines: Turtles, tortoises, and terrapins.
Order Crocodilia
Crocodilians are considered the most advanced reptiles based upon their heart.
Scales are covered with scutes that are shed individually.
They are found in warm/tropical climates because their stoop does not protect them against cold weather.
Crocodilians do not have sweat glands and open their mouths to release heat (panting just like dogs do to release heat).
They can run faster than humans, are good at climbing trees, and have a strong sense of smell, sight, and hearing.
Crocodilia Eyelids Structures
Consist of Three eyelids, with the innermost called the nictitating membrane.
The clear nictitating membrane acts as underwater goggles.
Tapetum reflects light to improve night vision but is only used with tapetum.
Gender Determination
Sex is determined by the temperature during egg development (not chromosomes).
Crocodilians replace their teeth throughout their lifetime and produce tears (crocodile tears).
Crocodilian Muscle Details
They have strong muscles for closing their mouths but weak muscles for opening them.
Crocodile Compared to Alligator
How to tell the difference between crocodile and alligator:
Alligators and caimans have a U-shaped snout, while crocodiles have a V-shaped snout.
Crocodiles have spots on their scales, while alligators do not ("crocs with spots, gators not").
When a crocodile closes its mouth, teeth from both jaws are visible. With alligators, only upper teeth are visible.
Crocodiles can live in saltwater due to salt glands; you will never find gators in salt water.
Crocodilian Digestion
Crocodile stomachs have very strong acid that has a pH of 1 to digest hard prey components.
Crocodiles do not chew and have strong acid for digestion of bones and other hard-to-break-down proteins.
They never stop growing, and they can get as large as 20' 3".
Order Sphenodonta
Contains only the tuatara in New Zealand.
"Tuatara" means "two peaks" in the Maui language.
Tuatara are ancient reptiles and are considered living fossils and are not closely related to lizards.
They are the least specialized of the reptiles
Tuatara vs. Lizard Distinctions
How to tell if this reptile is a Turatara, not a lizard.
Tuatara has a third eye in the top of their head; lizards do not.
Tuatara does not have visible ears.
Tuatara has front teeth; lizards do not.
Tuatara are nocturnal only; lizards can be active during the day and mostly inactive at night.
Tuatara teeth are projections of the jaw, act like teeth; lizards have real teeth.
Tuatara have very slow metabolism.
Turatara Life Span Details
Because of their slow metabolism, turataras live a long time (60-70 years or more).
Their numbers are declining because cats kill them and their reproduction rate is slow, so they are protected in New Zealand.
Order Squamata
Contains lizards and snakes. Snakes evolved from lizard-like ancestors.
Squamata Bone Structure
Squamata scales are horny.
They have bones called quadrate bones that connect lower and upper jaw.
These bones allow snakes to dislocate their jaws to swallow large prey.
Other Bone Characteristics
Primitive snakes like pythons have anal spurs, remnants of legs.
Skinks are a cross between snakes and lizards that look like snakes but have tiny arms and legs.
Reptilian Eyelid Details
Burrowing snakes have clear eyelids called a brill for protection.
How Snakes Take in Sensory Information Information
Snakes possess Jacobson's organs and pit organs for sensory input.
Jacobson's organ: Used along with their tongue, which picks up chemicals in the air; snake hunts food source to eat.
Pit organ: Used for detecting heat to sense prey heat from food source.
Coral Snakes
How to tell a coral snake versus a fake coral snake:
Red to black is a friend of Jack; red to yellow will kill a fellow.
Additional Venomous Snake Information
The most venomous snake is the inland taipan in Australia.
Different snakes have different venoms that affect the nervous system, blood clotting, and tissue breakdown.
More Snake FYIs
Flying snake fly through gliding.
Spitting cobra spits venom for temporary blinding, which does not really do any harm.
Order Testudines
Includes turtles, tortoises, and terrapins (chelonians).
Tortoises live on land.
Terrapins live in brackish water (salt marsh).
Turtles live in the ocean.
Chalonians Structures
Has two shells, shells are connected to their bones:
Carapace (top shell).
Plastron (abdomen shell).
Teeth/Cloaca and Aging
Modern chelonians do not have teeth but have jaw ridges.
Their butt is near the cloaca.
There is an opening used for waste and egg laying and extracting oxygen. Chelonians live in the water.
Aging and cells of old chelonians are very similar to those of young chelonians.