Chapter 29 Simple Invertebrates

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Chapter 29 Simple Invertebrates

• High School Biology Class

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Invertebrates

• Animals without backbones are known as the
  invertebrates.
• Examples snail, crab, spider, butterfly, clam,
  scorpion, etc.

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Phylum Porifera (Sponges)

• Simplest of all the animal phyla.
• Have an asymmetrical body plan.
• Are sessile (do not move from a spot once they
  attach themselves).
• Reproduce both asexually and sexually.
• Sponges can range from 1cm to 2m in size.

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Phylum Porifera (Sponges)

• Sponges siphon food through the ostia (water and
  food enter through these tiny pores).

• The larger openings where water leaves the
  sponge are called the oscula.

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Phylum Porifera (Sponges)

• First animals with multicellularity.
• Examples
• Calcareous sponge, Glass sponge, Demosponge

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Phylum Cnidaria (Cnidarians)

• Have a radial symmetrical body plan.
• There are two body shapes as well
• Medusa - free-floating, jelly-like, often
  umbrella-shaped.
• Polyp - tube-like and usually attached to a rock.

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Cniadarian Parts
Polyp
Medusa
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Phylum Cnidaria (Cnidarians)

• Bodies have stinging tentacles (called
  cnidocytes) that are used for defense and to
  spear their prey.
• Reproduce both asexually and sexually.

Digestion begins extracellularly and is completed
intracellularly.
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Cnidarian Lifecycle
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Phylum Cnidaria (Cnidarians)

• First animals with tissues.
• Examples
• Hydra, Man-of-war, Jellyfish, Comb Box jellies,
  Sea anemones, Corals (Reefs)

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Phylum Platyhelminthes (Flatworms)

• Have a bilateral symmetrical body plan.
• Have a mesoderm (middle layer).
• May be free-living organisms or parasites.
• Range in size from 1mm to several meters.

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Phylum Platyhelminthes (Flatworms)

• First animals with bilateral symmetry.
• Examples
• Turbellaria hermaphroditic marine flatworms
  that release undigested food out of their mouths
  and have two light-sensitive eyespots that give
  it a cross-eyed appearance.

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Phylum Platyhelminthes (Flatworms)

• Examples
• Cestoda - parasitic tapeworms, use hook
  structures to attach to intestines of their host
  (up to 40 feet long).
• Tapeworms live in muscle of cattle and therefore
  humans become infected when they eat undercooked
  beef.

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Phylum Platyhelminthes (Flatworms)

• Examples
• Trematoda - parasitic blood flukes, use suckers
  to attach themselves to hosts.
• Infection occurs when people swim in infected
  waters the parasites bore through the skin and
  then block blood passages.

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Phylum Nematoda (Roundworms)

• Have a bilateral symmetrical body plan.
• Have a one-way digestive system.
• Non-segmented organisms.
• Most are parasitic.

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Phylum Nematoda (Roundworms)

• First animals with a pseudocoelomate
• (body cavity, mouth, and anus).
• Examples
• Ascaris - eggs in the soil may become ingested
  (eaten).
• Once eaten they grow inside the intestine. The
  larvae then bore holes to get to the blood-stream
  and make their way to the lungs causing
  respiratory illness.

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Phylum Nematoda (Roundworms)

• Examples
• Trichinella - cause disease by eating
  under-cooked pork.

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Phylum Nematoda (Roundworms)

• Examples
• Necator - cause disease by bare feet stepping on
  larvae.

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Chapter 30 Mollusks and Annelids

• High School Biology Class

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Phylum Mollusca (Mollusks)

• The second largest animal phlya.
• Have a bilateral symmetrical body plan.
• Have excretion, digestion, circulation,
  respiration, and reproduction organ systems.
• May live in marine, freshwater, and/or
  terrestrial habitats.

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Phylum Mollusca (Mollusks)

• Body is divided into three parts
• 1) Visceral mass - contains internal organs.
• 2) Mantle - heavy covering of tissue that forms
  on the outside of the body.
• 3) Foot - muscular region or locomotion.

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Phylum Mollusca (Mollusks)

• Radula - rasping tongue-like organ located in the
  mouth.
• Have one or two shells (made of calcium
  carbonate) to protect their soft bodies.
• Trochophore larva, develop from the fertilized
  egg and are free-swimming, moves with cilia.

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Phylum Mollusca (Mollusks)

• First animals with a true coelom.
• Examples
• Gastropoda - snails and slugs
• Bivalvia - clams, oysters, and scallops
• Cephalopoda - octopi and squids

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Phylum Annelida (Segmented Worms)

• Have a bilateral symmetrical body plan.
• Have a coelom (body cavity).
• Have many organ systems including a closed
  circulatory system and modified gut.
• Have a cerebral ganglion (primitive brain).
• Setae - bristles for movement (traction).

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Phylum Annelida (Segmented Worms)

• First animals with segmentation.
• Examples
• Polychaeta - marine worms with many setae.
• Oligochaeta - earthworms (scavengers).
• Hirundinea - leeches (parasites).

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Any Questions?

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• --Ralph Waldo Emerson