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Classifying Invertebrates

Classifying Invertebrates. Of the million or more animal species in the world, more than 98% are invertebrates. Phylum Arthropoda crustaceans, insects, spiders, and relatives Arthropods are bilaterally symmetrical with strongly segmented bodies. They also have jointed appendages. Arthropods.

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Classifying Invertebrates

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  1. Classifying Invertebrates Of the million or more animal species in the world, more than 98% are invertebrates.

  2. Phylum Arthropodacrustaceans, insects, spiders, and relativesArthropods are bilaterally symmetrical with strongly segmented bodies.They also have jointed appendages.

  3. Arthropods

  4. Phylum Poriferasponges Sponges are a diverse group of sometimes common types, with about 5000 species known across the world. Sponges are primarily marine, but around 150 species live in fresh water. Sponges also provide a home for a number of small marine plants, which live in and around their pore systems.

  5. Porifera

  6. Phylum Echinodermata Echinoderm means "spiny skin." Echinodermata has approximately 7000 described living species and about 13,000 extinct species known from the fossil record. This phylum is the largest without any freshwater or terrestrial forms. Many grow out from a central radius. Some can regenerate broken or damaged extensions.

  7. Echinodermata(echinoderms)

  8. Phylum Cnidarianjellyfish, hydra, sea anemones, and coral Cnidarians have two basic body forms, medusa and polyp. Medusae, such as adult jellyfish, are free-swimming or floating. They usually have umbrella-shaped bodies. The mouth is usually on the concave side, and the tentacles originate on the rim of the umbrella. Polyps, in contrast, are usually sessile. They have tubular bodies; one end is attached to the substrate, and a mouth (usually surrounded by tentacles) is found at the other end. Polyps may occur alone or in groups of individuals.

  9. Cnidaria

  10. Phylum Platyhelminthesflatworms Planarians A planarian can be cut in two and each piece will grow into a new worm! In fact, there are even some kinds of planaria which can regenerate complete worms from almost any piece of their bodies. They reproduce asexually simply by dividing in two. Planarians can be found under rocks and in streams and ponds. Tapeworms They are parasites. These worms use hooks and suckers to attach themselves to the intestine of a host organism. Dogs, cats, humans and other animals are hosts for tapeworms.

  11. Platyhelminthes

  12. Phylum Nematodanematodes, roundworms Roundworms (nematodes) are bilaterally symmetrical, worm-like organisms that are surrounded by a strong, flexible noncellular layer called a cuticle. Their body plan is simple. Nematodes move by contraction of the longitudinal muscles. Because their internal pressure is high, this causes the body to flex rather than flatten, and the animal moves by thrashing back and forth. No cilia or flagellae are present. Many nematodes are free living and play critical ecological roles as decomposers and predators on microorganisms. But nematodes also include parasitic species, a number of which affect humans directly or indirectly through their domestic animals. These include the common roundworms, which probably infest more than half the world's humans; hookworms; trichina, the worms that cause trichinosis (from pork).

  13. Nematoda

  14. Phylum Annelidasegmented worms The annelids include earthworms and leeches. All members of the group are to some extent segmented, in other words, made up of segments that are formed by subdivisions that partially transect the body cavity. Members of the Phylum Annelida can be found throughout the world, in marine, freshwater, and terrestrial environments. Ecologically, they range from passive filter feeders to voracious and active predators.

  15. Annelida night crawlers earthworms leeches

  16. Phylum Mollusca(mollusks) Mollusks are soft-bodied invertebrates that usually have shells. They are found on land, in fresh water and in salt water. Many mollusks have bilateral symmetry and a fluid-filled cavity that provides space for the body organs. There are three basic types of mollusks: Univalves, also known as gastropods, have a single shell (except for slugs). This is the largest group of mollusks that includes snails and slugs. Bivalves have two shells joined by a hinge. Scallops, clams and oysters are examples of bivalves. Cephalopods do not have any shells. They are the most specialized and complex mollusks which include squid, octopus and cuttlefish (which are NOT fish!).

  17. Molluska univalves cephalopods bivalves

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