Phylum Annelida

What is a defining feature of the head in Phylum Annelida?

The head has a well-developed cerebral ganglion.

How are sensory organs arranged in Phylum Annelida?

Sensory organs are in ring-like segments.

Do many species in Phylum Annelida have eyes?

Yes, many species have eyes.

How are segments divided internally in Phylum Annelida?

Segments are divided internally by septa.

What does each segment in Phylum Annelida contain?

Each segment has a pair of excretory organs, a ganglion, and locomotory structures.

What type of circulatory system do organisms in Phylum Annelida have?

They have a closed circulatory system.

What type of nerve cord is found in Phylum Annelida?

They have a ventral nerve cord.

What type of worms are annelids?

Segmented worms

What is the body structure of annelids built from?

Repeated units

What advantage does segmentation provide to annelids?

Allows for specialization

How many times may segmentation have evolved in annelids?

Multiple times

What is specialized in each part of the digestive tract of annelids?

Different functions

What creates a hydrostatic skeleton in annelids?

Coelomic fluid

What allows for complex movements in annelids?

Alternating muscle contractions

What are chaetae in annelids?

Bristles of chitin found in most groups

How do annelids perform gas exchange?

By diffusion across body surfaces

What is the excretory system in annelids similar to?

Nephridia like mollusks

What are the two clades of Annelids

Errantia and Sedentaria

What are some examples of errantia?

Clamworms, scaleworms, lugworms, sea mice, tubeworms, and others.

What is a key feature of errantia regarding their body structure?

They have paired parapodia on most segments.

What is the function of parapodia in errantia?

Used in locomotion or gas exchange.

What type of structures do errantia have on their parapodia?

Chaetae.

Where may gonads be located in errantia?

In most segments or just certain segments.

What type of fertilization do errantia undergo?

External fertilization.

What type of larva do errantia produce?

Trochophore larva.

What is the term for organisms that show little movement?

Sedentaria

What type of habitat do many Sedentaria organisms burrow or live in?

Tubes

How do some Sedentaria organisms feed?

Using tentacles or filter-feeding

What is a notable characteristic of adult Riftia?

Adults are gutless

What type of bacteria are housed on Riftia?

Sulfur-oxidizing bacteria

What do sulfur-oxidizing bacteria synthesize for Riftia?

Organic compounds used by the worm

Where are Riftia typically found?

Near hydrothermal vents

What is a defining feature of the clade Clitellata?

All members have a clitellum.

What type of organisms are included in the clade Clitellata?

Earthworms.

How is the head of Clitellata characterized?

The head is not well differentiated.

Do Clitellata have parapodia?

No, they do not have parapodia.

How many chaetae project from the body wall of Clitellata?

Few chaetae project from the body wall.

What is the reproductive strategy of Clitellata?

They are hermaphroditic but cross-fertilize.

What does the clitellum secrete in Clitellata?

The clitellum secretes a mucus cocoon.

How many similar segments do earthworms have?

100-175

What projects from the body wall of earthworms?

Chaetae

How do earthworms obtain their food?

They eat their way through the soil.

Do earthworms have eyes?

No

What senses can earthworms detect?

Light, touch, and they have chemoreceptors.

What is the reproductive strategy of earthworms?

They are hermaphroditic and cross-fertilize.

Where do leeches mostly occur?

In freshwater

What is the body shape of leeches?

Usually flattened dorsoventrally

Are leeches hermaphroditic?

Yes

When does the clitellum develop in leeches?

Only during the breeding season

How is the coelom of leeches structured?

Reduced and not divided into segments

What features do leeches have at both ends of their body?

Suckers

Do leeches have chaetae?

No, except for one species

What do some leeches eat?

Detritus or blood