Life Cycle - Organisms (2A)

  • Discovering characteristics of animals.
  • Comparing and contrasting different characteristics of animals.
  • amphibian
  • bird
  • fish
  • fur
  • hair
  • mammal
  • reptile
  • scale
  • slimy
  • wet
  • live animals (we suggest a rabbit, bird, turtle newt or frog, fish, guinea pig or hamster)
  • worksheet

Students compare and contrast live animals.


The vertebrates refer to the phylum called CHORDATA. Members of this phylum are our common everyday animals. All mammals, birds, amphibians, reptiles, and fish belong to this group. There are over 45,000 species throughout the world. Vertebrates have a backbone, a nervous system, and a gill slit during some stage of their life cycle. In land-dwelling vertebrates, these slits are present only in the embryo.

Mammals have distinct characteristics including: controlled body temperature, highly developed jaws, a coat or hairy skin covering, highly developed internal organs, and mammalian glands. Most important is their mode of reproduction and the way in which the young are fed on the mother's milk.

Birds are warm blooded and have a constant body temperature (with some exceptions). Birds have succeeded in conquering the air by having a very light skeleton. The beak and eyes are highly developed. They have feathers and produce eggs.

Reptiles are mainly terrestrial, but there are many living partly in the aquatic environment. The body is covered with scales or patches of horny, sometimes bony skin. Limbs are usually short or absent, feet show many variations in form. Most reptiles are oviparous, meaning that they produce external eggs. Representatives of reptiles include lizards and snakes.

Amphibians are aquatic are four limbed. The most common characteristic is an exposed, water permeable skin, rich in glands which secrete mucus, which is sometimes poisonous. Amphibians lay small round eggs protected by a gelatinous mass. Some species go through a larval stage that metamorphoses into a juvenile, for example, a tadpole changes into a frog.

There are two major types of fish, one group called the bony fishes and the other cartilaginous fishes. All fishes live in water and have external fertilization (with some exceptions). Cartilaginous fish include sharks, rays, and lampreys. Bony include most of your present day fishes like tuna, salmon, and goldfishes.

  1. This activity requires live animals, which can be obtained or borrowed from a fellow teacher or by having students bring in their small pets. There is always one student who owns a rabbit, turtle, goldfish, hamster, guinea pig, mouse, or any other small animal.
  2. Discuss the following vertebrates characteristics with the students:
  • vertebrates have an endoskeleton (internal skeleton) made of bone or cartilage
  • vertebrates have a body with a head and trunk and many times a neck and tail
  • vertebrates have eyes, ears, and nostrils on the head
  • vertebrates also contain many highly developed systems associated with their specialized organs. The systems include the muscular, skeletal, digestive, respiratory, circulatory, excretory, nervous, and reproductive systems.
  1. Emphasize that humans are vertebrates. In the laboratory activity have the students describe the different animals that are brought to lab. On the lab sheet fill in the animal that is brought in on the left-hand column and on the right have the students describe the animal. You might want to develop a list of words that are more suitable for the animals that you have. You may want to compare the position of each animal's eyes, nose, and ears. Ask students to discuss why an animal looks the way it does. The correct answers are not as important as is having the children ask questions that compare and contrast the animals.

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