Overview of Invertebrate Phyla Characteristic

Traits of invertebrates

Porifera

Sponges

Habitat of porifera

Marine

How do porifera feed?

Filter feeding- water drawn through pores, absorbing nutrients from water

What are collar cells/choanocytes?

Specialized cells that use flagella to move a steady current through the sponge

What are spicules

Spike shaped structure made of calcium carbonate or silica that provide structure

What are amoebocytes/archeocytes

Cells that can move in the mesophyll that make spicules and digest food particles that collar cells get from water

How does the body of a porifera look like

1. Has no true tissue layers or organ systems (just the mesophyll layer and an epidermis) 2. Has a hollow body cavity with an opening at the top of the sponge that water circulates through

Symmetry of Porifera

Asymmetrical

Platyhelminthes

Flatworms

Habitat of Platyhelminthes

Aquatic or land

How do Platyhelminthes feed

1. Turbellarians (free-living)- Dead matter or tiny aquatic organisms 2. Flukes (parasites)- Internal organs 3. Tapeworms (parasites)- Inside intestines

How do Platyhelminthes reproduce?

Hermaphrodite- sexually and asexually

What is a scolex

Knob shaped head with hooks and suckers with which tapeworms attach to intestines

What are proglottids

Segment of tapeworms that have both male and female anatomy

What are eyespots

Cells that sense only light- not distinct shapes or images

What is a ganglia

Group of nervous cells that control nervous system- like a brain

How does the body of Platyhelminthes look like

3 germ tissue layers and internal organ systems

Cnidaria

Jellyfish, corals, sea anemones

Habitat of Cnidaria

Aquatic (mostly marine)

How do Cnidaria feed?

Use tentacles with stinging cells (cnidocytes) to capture and paralyze prey

What are cnidocytes?

Stinging cells that contain nematocysts to inject toxins

How does the body of a Cnidarian look like?

1. Radial symmetry 2. Two body forms: Polyp (sessile) and Medusa (free-swimming) 3. One body opening for both mouth and anus 4. Body has two tissue layers with a jelly-like layer in between

Symmetry of Cnidaria

Radial

Nematoda

Roundworms

Habitat of Nematoda

Soil, aquatic environments, or as parasites inside other organisms

How do Nematoda feed?

Decomposers or parasites; have a complete digestive tract (mouth and anus)

How does the body of Nematoda look like?

1. Bilateral symmetry 2. Unsegmented, cylindrical body 3. Pseudocoelom (fluid-filled body cavity) 4. Covered with a tough cuticle for protection

Reproduction of Nematoda

Mostly sexual with separate sexes

Symmetry of Nematoda

Bilateral

Annelida

Segmented worms (earthworms, leeches)

Habitat of Annelida

Soil, freshwater, or marine environments

How do Annelida feed?

Earthworms eat soil and digest organic matter; leeches suck blood or feed on small invertebrates

How does the body of Annelida look like?

1. Segmented body 2. Coelomate (true body cavity) 3. Bilateral symmetry 4. Closed circulatory system 5. Complete digestive system

Symmetry of Annelida

Bilateral

Reproduction of Annelida

Sexual (hermaphroditic in earthworms)

Mollusca

Snails, clams, octopuses

Habitat of Mollusca

Marine, freshwater, or terrestrial

How do Mollusks feed?

Snails use radula to scrape food, clams filter feed, octopuses are predators

Body features of Mollusca

1. Bilateral symmetry 2. Soft body with muscular foot, mantle, and visceral mass 3. Coelomate 4. Open or closed circulatory system

Symmetry of Mollusca

Bilateral

Reproduction of Mollusca

Mostly sexual, with separate sexes

Arthropoda

Insects, arachnids, crustaceans

Habitat of Arthropoda

Land, freshwater, marine

How do Arthropods feed?

Very diverse: herbivores, carnivores, parasites, scavengers

Body features of Arthropoda

1. Exoskeleton made of chitin 2. Segmented body: head, thorax, abdomen 3. Jointed appendages 4. Bilateral symmetry 5. Open circulatory system

Reproduction of Arthropoda

Sexual, separate sexes

Symmetry of Arthropoda

Bilateral

Echinodermata

Starfish, sea urchins, sea cucumbers

Habitat of Echinodermata

Marine only

How do Echinoderms feed?

Starfish use tube feet to open clams, sea urchins scrape algae, sea cucumbers filter feed

Body features of Echinodermata

1. Radial symmetry in adults 2. Endoskeleton made of calcium plates 3. Water vascular system 4. Tube feet for movement and feeding 5. Regeneration of body parts

Symmetry of Echinodermata

Radial (adults), Bilateral (larvae)

Reproduction of Echinodermata

Sexual (external fertilization)