Introduction to Animals

Vocabulary

1. homeostasis - The condition in which an organism's internal environment is kept stable in spite of changes in the external environment.
2. adaptation - An inherited behavior or physical characteristic that helps an organism survive and reproduce in its environment.
3. vertebrate - An animal with a backbone and a spinal cord.
4. invertebrate - An animal without a backbone.
5. tissue - A group of similar cells that perform a specific function.
6. organ - A body structure that is composed of different kinds of tissues that work together.
7. radial symmetry - A body plan in which any number of imaginary lines that all pass through a central point divide the animal into two mirror images.
8. bilateral symmetry - A body plan in which a single imaginary line divides the body into left and right sides that are mirror images of each other.
9. cnidarian - A radially symmetrical invertebrate that uses stinging cells to capture food and defend itself.
10. mollusk - An invertebrate with a soft, unsegmented body; most are protected by a hard outer shell.
11. arthropod - An invertebrate that has an external skeleton, a segmented body, and jointed appendages.
12. exoskeleton - External skeleton; a tough, waterproof outer covering that protects, supports, and helps prevent evaporation of water from the body of many invertebrates.
13. echinoderm - A radially symmetrical marine invertebrate that has an internal skeleton and a system of fluid-filled tubes.
14. endoskeleton - An internal skeleton; structural support within the body of an animal.
15. chordate - An animal that has a notochord, a nerve chord, and throat pouches at some point in its life.
16. notochord - A flexible rod that supports a chordate's back just below the nerve cord.
17. vertebrae - The bones that make up the backbone of an organism. In humans, one of the 26 bones that make up the backbone.
18. ectotherm - An animal whose body temperature is determined by the temperature of its environment.
19. endotherm - An animal whose body temperature is regulated by the internal heat the animal produces.
20. fish - A vertebrate whose body temperature is determined by the temperature of its environment (ectotherms), and that lives in the water and has fins.
21. cartilage - A connective tissue that is more flexible than bone and that protects the ends of bones and keeps them from rubbing together.
22. amphibian - A vertebrate whose body temperature is determined by the temperature of its environment (ectotherms), and that lives its early life in water and its adult life on land.
23. reptile - A vertebrate whose temperature is determined by the temperature of its environment (ectotherms), that has lungs and scaly skin, and that lays eggs on land.
24. bird - A vertebrate whose body temperature is regulated by its internal heat (endotherms), lays eggs, and has feathers and a four-chambered heart.
25. mammal - A vertebrate whose body temperature is regulated by its internal heat (endotherms), and that has skin covered with hair or fur and glands that produce milk to feed its young.
26. mammary gland - An organ in female mammals that produces milk for the mammal's young.
27. monotreme - A mammal that lays eggs.
28. marsupial - A mammal whose young are born at an early stage of development, and which usually continue to develop in a pouch on their mother's body.
29. placental mammal - A mammal that develops inside its mother's body until its body systems can function independently.
30. placenta - An organ in most pregnant mammals, including humans, that links the mother and the developing embryo and allows for the passage of materials between them.

General Knowledge

Characteristics of Animals

1. Are multicellular
2. Breathe oxygen
3. Respond to stimuli
4. Made of cells, tissues, organs and organ systems
5. Reproduce (most common way of reproduction is sexual reproduction)
6. Move (to look for food, to run from danger, to look for a new habitat)
7. Are heterotrophic/consumers (can't make their own food)
8. Some are capable of regenerating lost tissues or organs

Classification of Animals

• Invertebrates
  1. Sponges - Phylum Porifera (all sponges)
  2. Cnidarians - Phylum Coelenterata (jellyfish, sea anemones, hydra and coral)
  3. Flatworms - Phylum Platyhelminthes (planaria, tapeworm)
  4. Roundworms - Phylum Nematoda (hookworm, ascaris)
  5. Segmented Worms - Phylum Annelida (earthworms, leeches)
  6. Echinoderms - Phylum Echinodermata (starfish, sea cucumbers, sea urchins)
  7. Mollusks - Phylum Mollusca (squids, snails, clams, oysters)
     • gastropods
     • bivalves
     • cephalopod
  8. Arthropods - Phylum Arthropoda (subdivided into 3)
     • arachnids (millipedes, centipedes, spiders, scorpions)
     • insects (fly, mosquito, firefly, butterfly)
     • crustaceans (shrimp, lobsters)
• Vertebrates - Phylum Chordata
  1. Fish
  2. Amphibians
  3. Reptiles
  4. Birds
  5. Mammals

Vertebrates' Characteristics

• Its phylum is Phylum Chordata
• Have skeletons that may be make of bones, cartilage, or a combination
• Divided into fish, amphibians, reptiles, birds, and mammals
• Have a backbone to support and protect the spinal cord

Invertebrates' Characteristics

• No backbone
• No spinal cord
• No internal skeleton
• Some have an outer skeleton made of a material called chitin.
• Some have tentacles with stinging cells called nematocysts.
• Many invertebrates are marine animals.

Reproduction of Animals

• Most animals reproduce sexually
• Two cells are joined in a process known as fertilization, creating a developmental process that leads to a new life. The developmental stages are:
1. zygote
2. embryo
3. fetus
4. organism
• Some insects undergo a complete metamorphosis where all the stages are clearly identified:
1. egg
2. larva
3. pupa
4. adult
• Other insects undergo an incomplete metamorphosis where the young insect resembles an adult one and is called nymph.

Animal Behavior

• Animals exhibit two distinct behavior forms, these are:
• innate behavior - naturally occurring (nest building, spider web formation...)
• learned behavior - acquired through observation and practice (walking, speaking, writing, reading, flying...)
• Animals that live in groups display social behavior. Social behavior requires communication skills between the members of the group. Some animals that live in groups are:
• bees
• ants
• elephants
• lions
• wolves
• whales
• dolphins

Body Plans

• Symmetry deals with the organization and location of body parts
• There are several types of symmetry, they are:
  • radial - when all body parts have a common center
  • bilateral - when an imaginary line runs through the middle from north to south and identical body parts are on each side
  • assymetrical - animals with no symmetry (sponges)

Endotherms and Ectotherms

• Endotherms:
  • are warm-blooded
  • maintain a constant body temperature
  • birds and mammals are endotherms
• Ectotherms:
  • are cold-blooded
  • change their body temperature to the one in environment
  • fish, amphibians and reptiles are ectotherms

Fishes

• Fishes are divided into 3 groups, they are:
  1. jawless fish - Their "mouth" is round or circular in shape.
     • ex. remora, lampreys
  2. bony fish - skeleton made of bones
     • ex. chillo, dorado, goldfish, robalo, mero
  3. cartilage fish - skeleton made of cartilage
     • ex. sharks, stingrays, skates

Mammals

• Body covered with hair (fur)
• Feed milk to their young
• Are endotherms
• Have an internal skeleton
• Are divided into 3 groups
  1. placental - their young develop in the uterus and they have a placenta
  2. marsupials - are born very tender and finish their development in their mother's pouch
  3. monotrems - lay eggs

Adaptations

• In order to survive, some animals undergo different types of adaptations.
1. behavioral - migration, hibernation (rest in cold) and estivation (rest in heat) are three common behavioral adaptations
2. physical or structural - webbed feet, membranes that cover the eyes underwater, hollow bones in birds
• Animals respond to internal biological clocks that "remind" them of natural cycles.

REMEMBER TO READ YOUR NOTES AND STUDY FROM THE BOOK. YOU SHOULD ALSO STUDY FROM THE REVIEW GIVEN BY THE TEACHER.