Vertebrate Classes
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7 Classes of Subphylum Vertebrata:
This section lists the major classes within the subphylum Vertebrata, which includes animals with a backbone or spinal column. Each class represents a distinct group of vertebrates with unique characteristics.
Class Chondrichthyes: Includes cartilaginous fish like the Hammerhead Shark. These fish have skeletons made of cartilage rather than bone.
Class Osteichthyes: Includes bony fish like the Kelp Bass. These fish have skeletons made of bone.
Class Amphibia: Includes amphibians like the Tree Frog. These animals typically start their lives in water and later develop the ability to live on land.
Class Reptilia: Includes reptiles like the Day Gecko. These animals are characterized by scales and typically lay eggs on land.
Class Aves: Includes birds like the Broadbill. These are warm-blooded vertebrates with feathers, beaks, and wings.
Class Mammalia: Includes mammals like the Caracal. These animals have hair or fur, mammary glands, and typically give birth to live young.
Endotherms vs. Ectotherms:
This section differentiates between two types of organisms based on how they regulate their body temperature.
Endotherm: An organism that can maintain a constant body temperature, often referred to as "warm-blooded." They generate heat internally.
Ectotherm: An organism that cannot maintain a constant body temperature and relies on external sources of heat, often referred to as "cold-blooded."
Fish Classification:
This section outlines the classification of fish into different classes.
Class Agnatha: Jawless fish.
Class Chondrichthyes: Cartilaginous fish.
Class Osteichthyes: Bony fish.
What is a Fish?:
This section clarifies what animals are commonly called fish but are not actually fish and what animals are fish but do not have "fish" in their name.
Animals commonly called fish that are NOT fish: Jellyfish, Cuttlefish, Starfish, Crayfish, Shellfish.
Animals that ARE fish but don't have "fish" in their name: Seahorses, Eels, Sharks, Rays, Skates.
Adaptations of Fish:
This section discusses the various adaptations that fish have developed to survive in aquatic environments.
Body Shape: Streamlined for rapid movement in water.
Coloration: Countershaded, where the dorsal (top) surface is darker than the ventral (underneath) surface.
Fins: Membranous, wing-like or paddle-like organs used for propulsion, steering, or balancing.
Buoyancy: Bony fish store gases in their swim bladder, while cartilaginous fish store lipids in their liver.
Circulation: Two-chambered heart and single-loop blood circulation.
Efficient Respiration: Internal gills for gas exchange, which fan out in water and have a large surface area.
Homeostasis: Maintain concentrations of salt and water that differ from their surroundings.
Respiration Process in Fish:
This section describes the steps involved in how fish breathe.
Water enters through the mouth.
Oxygen is extracted by the gills.
Water exits through the gill cover.
Osmosis Review:
This section provides a brief overview of osmosis, a key process in maintaining fluid balance.
Osmosis: Liquid moves from a region of low solute concentration to a region of higher solute concentration to equalize solute concentrations.
Homeostasis in Marine Bony Fish
Hypoosmotic regulators.
Tissues are less salty than surrounding water, leading to water loss.
Drink large amounts of water and produce a small amount of concentrated urine to prevent dehydration.
Gills secrete salt.
Homeostasis in Freshwater Fish
Hyperosmotic regulators.
Tissues are saltier than surrounding environment, leading to water gain.
Do not drink water and produce large amounts of dilute urine.
Sensory Adaptations of Fish:
This section details the sensory systems that fish use to perceive their environment.
Sight: Eyes similar to land vertebrates; most fish lack eyelids, but some sharks do.
Sound: Internal ears receive vibrations from water through their body.
Smell and Taste: Chemoreception, the ability to detect chemicals in the environment through nostrils (nares) and taste buds, which can be in the mouth, lips, fins, skin, and barbels (whisker-like organs).
Lateral Line System: Canals in skin that sense vibrations in the water, composed of neuromasts (receptor organs sensitive to vibration and water currents).
Ampullae of Lorenzini: Organs in cartilaginous fish's head that detect bioelectric fields generated by living animals (muscles).
Classification of Fish:
This section outlines the taxonomic classification of fish.
Kingdom Animalia, Phylum Chordata, Subphylum Vertebrata
Four Classes of Fish: Osteichthyes (Bony fish, about 96% of all fish species), Chondrichthyes (Cartilaginous fish), Myxini (Hagfish), Cephalaspidomorphi (Lampreys).
Class Agnatha (Jawless Fish):
This section describes the characteristics of jawless fish.
Examples: Lamprey & Hagfish
Heart: 2 chambers
Respiration: Gills
Fertilization: External in H2O
Egg: Small, no shell (must be in water or dries out), yolk (food)
Metabolism: Ectotherm
Skin: Scaleless and soft
Other: Notochord but no bones, no jaws; Lamprey (parasite on whales, fish & dolphins with sucker-like mouth, teeth & rasping tongue); Hagfish (scavenger on the ocean floor).
Class Chondrichthyes (Cartilaginous Fish):
This section details the traits of cartilaginous fish.
Examples: Sharks, skates & rays
Heart: 2 chambers
Respiration: Gills
Fertilization: External in water or internal
Egg: Small, no shell, yolk
Metabolism: Endotherm
Skin: Scales & sensory organs
Endoskeleton of cartilage
Sharks have rows of teeth.
Class Osteichthyes (Bony Fish):
This section describes the characteristics of bony fish.
Examples: Salmon, eels, seahorse, trout, tuna, porcupine fish
Heart: 2 chambers
Respiration: Gills
Fertilization: External in water
Egg: Small, no shell, yolk
Metabolism: Ectotherm
Skin: Scales
Other: Swim bladder regulates buoyancy; some species can spend time out of water (lungfish).
Amphibians:
This section provides an overview of amphibians.
Examples: Axolotl, caecilian, frog, newt, salamander, toad
Small vertebrates that need water or a moist environment to survive; can breathe and absorb water through their thin skin.
Special skin glands produce useful proteins for transporting water, oxygen, and carbon dioxide; fighting bacteria or fungal infections; defense (e.g., Curare from poison dart frogs).
Life Cycle: Egg-larva-adult; larvae are aquatic and free-swimming (tadpoles), develop limbs and lungs, lose their tails, and undergo metamorphosis to become adults on land.
Cold-blooded and require specific living conditions; sensitive to habitat disturbances and chemical contamination; over half of all frog species are in danger of extinction.
Class Amphibia:
This section describes the characteristics of amphibians.
Examples: Frogs, toads, newts, salamanders, caecilian (legless)
Respiration: Gills/lungs (inefficient), skin, and mouth lining
Fertilization: External
Egg: Small, no shell, yolk
Metabolism: Ectotherm
Skin: No claws or scales – Smooth, moist skin – Some have poison glands
Heart: 3 chambers
Other: No ribcage; if skin dries out it will suffocate, so tied to water; Amphibia means “2 lives” (water & land); eats insects, worms, small birds/fish/mammals.
Heart Structure Comparison:
This section compares the heart structures of fish, reptiles/amphibians, and mammals.
Fish Heart: One Atrium, One Ventricle ("Single Circulation").
Reptile/Amphibian Heart: Two Atria, One Ventricle (both oxygenated and deoxygenated blood are mixed) ("Double Circulation").
Mammalian Heart: Two Atria, Two Ventricles (oxygenated and deoxygenated blood separate) ("Double Circulation").
Characteristics of Reptiles:
This section outlines the general characteristics of reptiles.
Vertebrates - Possess a backbone.
Produce Eggs - Most lay hard-shelled eggs, but some give birth to live young
Scales or Scutes - Made from keratin (scales) or bony structures (scutes) to provide physical protection and prevent water loss.
Ectothermic - Cannot control their own body temperature and rely on the environment to regulate body temperature.
Reptilia:
This section provides a general description of reptiles.
Adapted to terrestrial environments; characterized by scales, amniotic eggs, and waterproof skin.
Exhibit bilateral symmetry and have a backbone for rigidity and support.
Reptilian Physiology:
This section details the physiological characteristics of reptiles.
Ectothermic: Rely on external heat sources to regulate body temperature.
Circulation: Typically have a three-chamber heart (except some crocodilians with a four-chamber heart).
Respiration: Primarily through lungs.
Nervous System: Well-developed, including a brain and spinal cord.
Excretion: Carried out by cloaca; excrete nitrogenous wastes in the form of uric acid.
Reproduction: Reproduce sexually, laying amniotic eggs. Some give birth to live young.
Class Aves (Birds):
This section describes the characteristics of birds.
Examples: Hawk, eagle, penguin, robin, owl, ostrich
Warm-blooded (endotherm) vertebrates adapted for flight, characterized by feathers, beaks, and a high metabolic rate.
Bird Anatomy and Physiology:
This section covers the anatomy and physiology of birds.
Bilateral Symmetry: Essential for aerodynamic efficiency during flight.
Bony Skeleton: Pneumatized (hollow) bones reduce weight, with a keel bone on their sternum where the flying muscles attach.
Four-Chamber Heart: Efficient separation of oxygenated and deoxygenated blood.
Endothermic: Maintain a constant and elevated body temperature.
Respiration: Air sacs allow for one-way airflow, enabling continuous gas exchange.
Nervous System: Well-developed, allowing for complex behaviours.
Bird Digestion, Excretion, and Reproduction:
This section details the digestive, excretory, and reproductive systems of birds.
Digestion: Complex system with a crop and gizzard.
Excretion: Eliminate waste through the cloaca in the form of uric acid or guanine.
Reproduction: Reproduce sexually through internal fertilization, laying amniotic eggs; ovaries and testes are reduced when it is not breeding season.
Bird Adaptations:
This section discusses the various adaptations that birds have developed.
Beaks: Specialized for various feeding behaviors.
Feet and Claws: Adapted for perching, swimming, grasping prey, or digging.
Feathers: Serve multiple functions, including insulation, protection, and enabling powered flight; composed of keratin.
Tail feathers are balanced left and right of the center. Flight feathers have a wider and narrower side. Down feathers are good for warmth and insulation. Semiplume feathers also hep to keep birds warm and they help water birds float. The bristle feathers are found around the eyes and nostrils and filoplume feathers can be found around the tail and flight feathers. They are thought to be used to sense when flight feathers need to be maintained.
Class Aves - Unique Adaptations:
This section highlights some unique adaptations of birds.
Excrete uric acid (solid) to decrease water and reduce weight; no bladder needed.
Elongated wing-like hand.
Alveoli (air sacs) make the bird more buoyant and allow for more efficient gas exchange.
Class Mammalia:
This section describes the characteristics of mammals.
Examples: Humans, cats, dogs, horses, koala, whale, duckbilled platypus
Vertebrates characterized by mammary glands, hair or fur, and a four-chamber heart.
Mammal Main Classes:
This section lists the main classes of mammals.
Rodents
Carnivores
Cetacea
Primates
Mammalian Characteristics:
This section details the general characteristics of mammals.
Bilateral Symmetry: Allows for efficient movement and coordinated locomotion.
Support and Circulation: The skeleton of mammals is typically composed of spine and ribcage providing structural support and protection for internal organs.
Four-chamber heart: Ensures efficient separation of oxygenated and deoxygenated blood.
Sinoatrial (pacemaker): Determines when the heart beats.
Endotherm.
Mammalian Respiration & Reproduction:
This section describes the respiratory and reproductive systems of mammals.
Lungs in the thorax are protected by the thoracic cage; diaphragm and intercostal muscles facilitate pumping action on the lungs.
Reproduce sexually, and most species give birth to live young; offspring are nourished with milk produced by the mammary gland.
Reproductive Groups of Mammals:
This section outlines the different reproductive groups within mammals.
Placental mammals (Eutherians): Have a placenta for food, waste, and