J.5 Roundworms

What major body plan advancement do roundworms have compared to flatworms?

A complete digestive tract with a separate mouth and anus.

What type of digestive system do roundworms have?

Tube-like (one-way) digestive system.

How does a tube-like digestive system differ from a sac-like digestive system?

t has separate openings for food intake (mouth) and waste removal (anus).

What body cavity do roundworms possess?

A pseudocoelom.

How is the pseudocoelom formed?

By separation of the endoderm from the mesoderm.

 

 What is a pseudocoelom?

A body cavity partially lined with mesoderm.

Why is the pseudocoelom important evolutionarily?

It is an intermediate step between no body cavity and a true coelom.

What are animals with a pseudocoelom called?

Pseudocoelomates.

What are flatworms called because they lack a body cavity?

Acoelomates

Is the digestive tube completely surrounded by mesoderm?

no

Can the digestive tube move independently of the body wall?

not completely

Do pseudocoelomates have a circulatory system?

no

How is a true coelom different?

Mesoderm lines both sides of the cavity.

What advantage does a true coelom provide?

Independent movement of digestive organs.

What additional system develops with a true coelom?

Circulatory system.

Are many roundworms free-living or parasitic?

Parasitic

What is a common parasitic roundworm?

Ascaris

Where does Ascaris live?

Vertebrate Intestines

What does Ascaris feed on?

Nurtrients intended for the host.

What serious condition can large Ascaris infections cause?

Intestinal blockage

What system does the filaria worm infect?

Lymphatic system

What is the function of the lymphatic system?

Returns excess fluid to circulation and supports immunity.

What happens when filaria worms block lymph flow?

Swelling (edema)

what is edma?

Swelling caused by fluid buildup.

What severe disease can untreated filaria infections cause?

Elephantiasis

What is elephantiasis?

Extreme swelling and enlargement of limbs due to blocked lymph vessels.

Why are parasitic roundworms less specialized?

They live in stable environments inside hosts.

Why don't parasitic roundworms need complex nervous systems?

They don't need to actively search for food or respond to many environmental changes.

What do parasitic roundworms typically digest?

Host body fluids and nutrients.

Why can their digestive systems be relatively simple?

Food is readily available inside the host.

What type of muscles do roundworms possess?

Longitudinal muscles only.

: Do roundworms have circular muscles?

No

How do roundworms move?

By lashing side to side

What else does this lashing motion help accomplish?

Moving food through the digestive tract.

Do roundworms have a circulatory system?

No

Do roundworms have a skeletal system?

No