Chapter 1 Invertebrates 1:1  Classifying Animals

Organism-any living thing
Classification-the process of grouping organisms by using similar characteristics (ways they are alike)
Animals can be divided into 2 main groups:
    Vertebrate-animal WITH a backbone
    Invertebrate-animal WITHOUT a backbone Classifying invertebrates  


1.  Sponges
2.  Stinging-celled animals
3.  Flatworms
4.  Roundworms


5.  Mollusks
6.  Segmented worms
7.  Arthropods
8.  Spiny-bodied animals

  1:2  Simple Invertebrates

A.  Every living thing is made of cells.
B.  Cell-smallest unit of an organism that can carry out all the activities of life
C.  Different cells that work together to do the same job form a tissue.
D.  Groups of tissues that work together form an organ.
E.  Organs that work together form a system.

1.  Sponge-simplest invertebrate
                -made of 2 layers of cells
                -food and oxygen flow in and out of cells
                -can regenerate
                -live in water
    Regeneration-the ability to regrow cells or parts of an organism that have been damaged.

2.  Stinging-celled animal-made of 2 layers of cells that form 2 kinds of tissues
                                        -has one opening (mouth)
                                        -has tentacles
                                        -can regenerate damaged body parts
                                        -live in water
    Tentacles-ropelike parts that contain stinging cells
    Examples:  jellyfish, hydra, sea anemone, coral

3.  Flatworm-has organs for moving, digesting food, and releasing wastes
                    -has only 1 opening
                    -can regenerate
                    -many are parasites
                    -some are scavengers
    Parasite-an organism that feeds on and causes harm to another organism called a host
    Example:  tapeworm

    Scavenger-animal that eats dead or rotting organisms
    Example:  planarian

4.  Roundworm-has specialized tissues
                        -has 2 body openings connected by a long tube; food goes in one opening
                          and wastes go out the other
                         -many are parasites; one kind lives in pigs (always cook pork thoroughly)
  1:3  Complex Invertebrates

5.  Mollusk-soft-bodied invertebrate that may produce a shell
                    - lives on land or in water
                    -second largest group of animals
    Examples:  octopus (no shell)
                        snail (1 shell)
                        clam, oyster (2 shells with a hinge)
                        squid (small shell inside body)

6.  Segment worm-has organs that make a circulatory system
                            -body is divided into sections (segments)
    Examples:  night crawler, earthworm

7.  Arthropod-animal with an outer skeleton (called "exoskeleton"), jointed legs, and a segmented
                      -largest group of animals

    Groups of arthropods:
        Centipede- 1 pair of legs on each segment
        Millipede-2 pairs of legs on each segment
        Crustacean-have claws and hard exoskeleton (crab, crayfish, shrimp, lobster)
        Insect-3 body sections, eyes, feelers, 3 pairs of legs,
                    many have wings (bee, fly, ant)
        Arachnid-4 pairs of legs, 2 body sections, no wings, no feelers
                        (spider, tick, mite, scorpion)

The insects form the largest group of arthropods.

8.  Spiny-bodied animal-complex invertebrate
                                    -skeleton of plates
                                    -some have spines for protection
                                    -has tube feet (feet with suction cups)
    Examples:  sea urchin, starfish

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