Invertebrates

6 major Invertebrate Phyla

• Porifera- sponges• Cnidaria-sea anemones and jellyfish• Mollusca- snails, slugs, squids, and octopuses• Annelida- segmented worms(repeated body

segments)• Arthropoda- insects, shrimps, lobsters, and

crabs• Echinodermata- sea stars, urchins, brittle stars

- Two sides of the body mirror each other

- There is no line of symmetry

- Symmetry is found all around the center point

Bilateral

3 Main Body Plans

Invertebrate

1. Bilateral

- Organism without a backbone

Radial

3. Asymmetrical2. Radial

Asymmetrical

- Space surrounding the gut- Can have other organs within

Ganglion

- All animals except sponges have nerves

Gut - A pouch lined with cells, used to break down food, the cells absorb the food

- Concentrated mass of nerve cells

Coelom

- Nerves allow animal to sense environment

Invertebrate Characteristics

- Live in water

Regeneration

- Simplest invertebrates

- Asymmetrical, no tissues, gut or neurons

- Can regenerate broken or missing parts- Classified by their shapes- Ability to grow back a body part

Sponges- Porifera

Pores -Holes on the outside of body-Water brings in food and oxygen

Osculum -Hole on top of sponge that allows water to leave

- Swims through waterMedusa

- Ex: Jellyfish, Anemones- Two body forms: Medusa or Polyp

- Usually attach to a surface

- Radial symmetryCnidarians

Polyp

-complex tissue and a gut-simple nerve cells-stinging cells

Classes of CnidariansHydrozoans -common cnidarians

-live in both fresh and salt water-most spend lives as polyps

Jellyfish -use tentacles to catch food-spend most of lives as medusas

Sea anemones -brightly colored-spend lives as polyps

Coral -polyps-brightly colored-made of calcium carbonate-live in colonies-build underwater reefs- Found in warm, tropical waters

Nematoda

- Many are parasites Trichinella spiralis- Some infect humans pinworms and

hookworms- decomposers

- Simple nervous system- Simple brain is a ring of ganglia

- Bilateral symmetryRound Worms (long, slim, & round)

- Cannot see through eyespots, but sense light

- Clearly defined head- Two large eyespots

Planarian

- Bilateral symmetryFlatworms (simplest worms)

- Some can be parasitic- Microscopic- 3 major types

-Live in freshwater lakes and streams-predators-well developed nervous system

Flukes -parasites-feed on a host organism-no eyespots-contain suckers and hooks to attach to other animals

Platyhelmenthes

Tapeworm -parasites-no gut or eyespots-attach to the intestines of other animalsAbsorb nutrients-can infect humans

Mollusks and Annelid Worms

Mollusks-Most live in the ocean-some live in freshwater and land

-complex ganglia-control breathing, movement, &digestion

-contain a circulatory system- pump blood

-Bodies are made of :-Muscular foot-used for movement-Visceral mass- contains gut, gills, and other organs

-Mantle-covering used for protection if no shell, covers the visceral mass

-Shell-hard covering used for protectionfrom predators or land mollusks from drying out

Gastropods -slugs and snails-eat by using a radula tongue with curved teeth

3 Classes of Mollusks

Bivalves - 2 shells

-clams, oysters and other shellfish-use gills to filter food from water(tiny plants,bacteria)

Cephalopods -Octopus and squid-use tentacles to get food and a powerful jaw to eat it

-contain large brain connected to ganglia-most advanced nervous system, smartest invertebrates

Annelid Worms-segmented worms

-bodies are in segments identical repeating body parts-bilateral symmetry-circulatory system-Complex nervous system with brain-Live in salt water, freshwater or on land

-3 major groups

Earthworms -most common-decomposers

-leave casting(waste product)in soil produce rich soilUse stiff hairs or bristles to move

Marine Worms -Colorful-Live in ocean-Polychaetes covered in bristles “Many bristles”-Eat mollusks or filter water for food

Leeches -Parasites that suck blood produces a chemical that thins blood can be used medically-Scavengers that eat dead animals

Arthropods and Echinoderms

4. Well developed nervous system3. External Skeleton (Exoskeleton)

Segmented bodySpecialized structures

Four Characteristics Shared by Arthropods1. Segmented and specialized body2. Jointed limbs- “athro”(joint) “pod”(foot)

- Body parts bend at joints

-head, thorax, and abdomen

Wings, antennae, gills, pincers, claws

Exoskeleton – hard covering of the body

Nervous systemAntennae- feelers that sense touch, taste, and smell.Compound eye- several identical light sensitive units.Brain/nerve cord

Ex: Shrimp, Crab, Lobster- Have two compound eyes

Mandible

Crustaceans- Have gills, antennae, and mandibles

- Mouthparts that can pierce objects and chew

- Simple eyes- 4 pairs of legs, no antennae

Arachnids- 2 body parts: Cephalothorax and Abdomen

-spiders, scorpions, mites, ticks

- 3 main body parts-head, thorax, abdomen- Six legs

Insects- Largest group of arthropods

- 2 antennae

Metamorphosis

- Grows from smaller youth to larger adult- 3 stages: egg ,nymph, adult

Complete Metamorphosis

- Change from young to adult

- Organism goes through a complete change- 4 stages: egg, larva, pupa, adult

- No major changes in organismIncomplete Metamorphosis

- Internal skeleton made of bones or cartilage

- Means “spiny skinned”

Endoskeleton

Echinoderms

Ex: Sea stars(starfish), Sand Dollars

- Simple nervous system- contains a mouth (nerve ring)

- Radial symmetry

- System of canals filled with fluidWater Vascular System

- Used to move, eat, sense environment, breathe- Circulates water throughout the body

Types of Echinoderms

Brittle Stars Basket Stars

Sea UrchinsSand Dollars

Sea LiliesFeather Stars

Sea Cucumbers

-long slim arms-smaller than sea star

-round with no arms-shell-like structure

-use spines and tube feet to move

-have multiple feathery arms

-no arms and worm-shaped-soft, leathery body