Zoology

• Animals with a backbone are called vertebrates. Vertebrates belong to Phylum Chordata; thus, they are called chordates. There are five groups within Phylum Chordata: 1) fishes 2) amphibians 3) reptiles 4) birds and 5) mammals.
• Fishes


  • Best adapted to underwater life, Cold-blooded vertebrates
• Support and Movement of Fishes

  • Covered with scales, Move by means of their fins, Possess a skeleton either made of bones or cartilage
• Classes of Fishes


  • Class Agnatha (possess a cartilaginous skeleton, Examples: lamprey, hagfish)
  • Class Chondrichthyes (Cartilaginous skeleton, Examples: skate, ray, sharks)
  • Class Osteichthyes (Possess a bony skeleton, Examples: coelacanth, salmon, puppy, tuna, milkfish, tilapia)
• Digestion in Fishes


  • Consist of mouth, stomach, intestines, and accessory organs such as liver, and gall bladder
• Respiration in Fishes


  • Breathe through gills, except for lungfish which possess lungs that serve as their modified swim bladder
• Reproduction in Fishes


  • Undergo internal and external fertilization
• Adaptations in Fishes


  • Camouflage to blend with their surroundings, Schooling behaviour
• Economic Importance of Fishes

  • Source of protein, Provides employment opportunities, Outdoor activity, Control of mosquito populations
• Not all fishes have a swim bladder
• The swim bladder is present in most bony fishes. It is missing in some bottom-dwelling and deep-sea bony fish (teleost) and in all cartilaginous fish (sharks, skates, and rays). A swim bladder is a gas-filled sac that gives it buoyancy or the ability to float on water.
• Amphibians are cold-blooded (ectotherm) vertebrates. Amphibians spend part of their lives in water and part on land. Examples are toads, frogs, salamanders, and newts.
• Support and Movement of Amphibians

  • Covered with smooth and slimy skin, Move by means of their limbs with webbed feet except for caecilians
• Digestion in Amphibians


  • Have a complete digestive tract from mouth to cloaca (serves as the only opening for the intestinal, reproductive, and urinary tract)
• Respiration in Amphibians


  • Breathe through gills as larvae and through lungs as an adult
• Reproduction in Amphibians


  • Frogs and toads undergo external fertilization, Caecilians and salamanders undergo internal fertilization, Eggs are covered with a jelly-like coating that must be kept moist, Most amphibians undergo metamorphosis (There is no actual metamorphosis in newts)
• Adaptations in Amphibians


  • Possess sticky pads on their toes to climb trees and webbed feet for swimming
• Economic Importance of Amphibians

  • Useful in the reduction of pest insects, Serve as a food source for predators, Skin secretions used in some painkillers and high blood medications, Study of their ability to regenerate limbs may contribute to tissue regeneration, Presence indicates a healthy ecosystem
• The smallest amphibian is the Paedophryne amouensis, discovered in Papua New Guinea. It is also known to be the smallest vertebrate. The Chinese giant salamander, on the other hand, is the largest amphibian, capable of growing nearly 6 feet in length (1.8 meters). It is a "living fossil" having seen the dinosaurs come and go.
• Reptiles are cold-blooded (ectotherm) vertebrates. Examples are turtles, snakes, crocodiles, geckos, and other lizards.
• Support and Movement of Reptiles

  • Covered with hard and dry scales made up of keratin, Move by means of their limbs and claws for digging, running, and climbing
• Digestion in Reptiles


  • Simply bite or tear food into pieces small enough to swallow, Food is mainly digested by the enzymes in the stomach, making digestion a long and slow process
• Respiration in Reptiles


  • Breathe through their lungs
• Reproduction in Reptiles


  • Undergo internal fertilization, Most lay eggs protected in a hard shell, Some snakes like rattlesnakes may give birth to live young, Reproductive activity occurs within the cloaca
• Adaptations in Reptiles


  • Geckos, skinks, and other lizards have disposable tails that grow back to distract predators, Presence of thick skin that minimize water loss
• Economic Importance of Reptiles

  • Lizards help to control insects, Snakes contribute to the control of rodents, Some reptiles are important as food sources, Skin of snakes, lizards, crocodiles, and alligators is used to make leather, Provide models for examining physiological mechanisms such as body heat
• Birds are warm-blooded (endotherm) vertebrates. Examples are eagles, chickens, ducks, owls, finches, and penguins.
• Support and Movement of Birds

  • Covered with feathers, Move by means of their light yet strong bones for flight
• Digestion in Birds


  • Consist of beak, crop (moistens and stores the food), and gizzard (part of the stomach that grinds the food)
• Respiration in Birds


  • Breathe through their small lungs
• Reproduction in Birds


  • Undergo internal fertilization, Lay eggs protected in a hard shell, Reproductive activity also occurs within the cloaca
• Adaptations in Birds


  • The shape of their beaks and feet reflects the type of food and habitat they are adapted to, Possess keen eyesight, Migration-movement from areas of low or decreasing resources to an area of high or increasing resources
• Economic Importance of Birds

  • Source of food, Popular as pets, Feathers used as insulation, Droppings used as fertilizer, Help in pollination and seed dispersal
• Mammals are warm-blooded (endotherm) vertebrates. Examples are duck-billed platypuses, whales, dolphins, kangaroos, koalas, pigs, horses, and bats.
• Support and Movement of Mammals

  • Covered with hair or fur, Move by means of their limbs or legs
• Digestion in Mammals


  • Have a complete digestive tract from mouth to anus and accessory organs such as liver, gall bladder, and pancreas
• Respiration in Mammals


  • Breathe through the lungs
• Reproduction in Mammals


  • Undergo internal fertilization, Give birth to live young, Female mammals have mammary glands which nourish their young with milk
• Adaptations in Mammals


  • Possess insulating layers such as a thick coat of fur or a thick layer of fat to retain body heat during cold climate, Ability to go into an inactive state resembling a deep sleep during winter (hibernation) and prolonged dormancy during summer or hot and dry periods (estivation) or when the food is scarce
• Economic Importance of Mammals

  • Domesticated mammals provide meat and meat products, Cows, goats, buffalos, and other mammals provide milk, Hides (skin) and furs used in manufacturing, Wool used in weaving clothes, Horses, buffalos, and carabaos employed in plowing fields