Marine Worms

Flatworms, Annelids, & Polychaeates

Evolution in progress!!

• Going from sponges – Multi cellular

• No sensory organs • No locomotion • No cognitive

functioning • No organs

– Sessile – Asymmetrical

To Worms!

• organ level of organization! – What organs did you find

in the worksheet?

• Bilateral symmetry • Cephalization

– Beginnings of a brain

• Locomotion • Active predators

Phylum platyhelminthes

Class turbellaria

Flatworms!

• Cephalization – Can detect light,

chemicals, and movement

• Locomotion – Covered with a layer of

cells called the epidermis – Ventral surface of

epidermis produces mucus

Flatworms

• Digestion: – Heterotrophs

• Crustaceans, snails, annelid worms

• Bodies of dead animals

• Diatoms – Why is it more

beneficial to eat diatoms?

Active predators

• Entangle prey in mucus– Suffocates

• Stab prey with a pharynx– Pumps out enzymes – Sucks out body fluids

• Gastrovascular cavity – What do the branches in

the cavity do for the organism?

Flatworms

• Reproduction – Asexually and

sexually • regeneration

• Reciprocal copulation – Hermaphrodites – Exchange both

sperm and egg

Tapeworms

• Parasitic– Live in digestive tract – Can be huge

• No digestive tract or nervous tissue

• Passed through intermediate hosts – Can be deadly

• Attach to host using a scolex

Phylum Annelida

Segmented worms

Annelids

• Worms whose bodies are divided internally and externally into segments

• Heterotrophs – Take in nutrients

from the soil – help to filter nutrients

Structure of annelids

• Bilateral – Fluid filled: hydrostatic

skeleton

• Longitudinal and circular muscles to help with locomotion

• Setae: – bristles on skin that help

movement

• Cerebral ganglia • Gas exchange occurs

across the skin

Digestion

• Food enters body through the pharynx – Organic nutrients are

digested in the intestine

• Nutrients are stored in the crop

• Help to filter nutrients in the soil

Class polychaetes

Tube like worms

• Live in sand mud, corals, shells

• Bury themselves in the sand and project only their jaws or tentacles out of their tubes

Structure

• Light sensors – pull themselves back in

their tubes

• Tentacles – Use cilia to strain food

and release wastes

• Tubes – Protective – Made of calcium, carbon, – Structure

Digestion

• Digestive tract running straight through – Usually two openings – Or turn themselves

inside out to release wastes

Reproduction • Asexual:

– regeneration, budding

• Sexual: – Epitoke: pelagic

reproduction • Release millions of

sperm and eggs all in one night