BIOL 112 Lab 13 Flatworms and Roundworms

How are flatworms and roundworms similar?

Both are triploblastic (3 body tissue layers), bilaterally symmetrical, and they lack a circulatory system for transporting oxygen and nutrients to internal organs

Phylum Platyhelminthes

Flatworms

Phylum Nematoda

Roundworms

Flatworms lack ___

A body cavity

Nematoda have a ___

Fluid-filled body cavity containing internal organs. Derived from the blastocoel

Blastocoel

Primitive cavity that is found in the embryo and persists as the pseudocoelom in the adult

How is oxygen and nutrients delivered in flatworms (phyla platyhelminthes)

The gastrovascular cavity

How is oxygen and nutrients delivered in roundworms (phyla Nematoda)

Movement of fluid in the pseudocoelom

Which phyla has a complex digestive system with two openings (mouth/anus) and posses an outer covering called a cuticle?

Nematoda, or roundworms

Traits of flatworms (platyhelminthes)

Dorsoventrally flattened, no body cavity

Cephalization

Concentration of sense organs, and nervous controls in the anterior end (forms head and brain)

Flatworms use their epidermis as a ____

Respiratory surface

What is the space between the surface epidermis and the linings of the gastrovascular cavity in planarians (phyla plathelminthes)

Mesenchyme

How are the muscle of the planarian arranged?

In 2 layers, one circular and one longitudinal. Also a set of dorsal-ventral muscles

Host organism that harbors sexually mature parasite is called _____

Definitive host

What host organism carrier the larval stages of a parasite?

The intermediate hosts

How do parasites compensate for the complicated life cycle?

High reproductive rate, more likely for off spring to survive the journey

Parasitic platyhelminthes

Flukes, one of the most common types of parasitic worms

What is the intermediate host for a sheep liver fluke (fasciola)

Snail

Fasciola produce both egg and sperm, this is called ____

Hermaphroditic

Where is the female reproductive system found in fasciola?

Anterior half (top)

What happens after a fasciola infects a snail (intermediate host)?

They develop into the second larval stage called cercariae

How do fasciola get from the intermediate host to the definitive host?

They leave the snail and form cyst on vegetation, which is then consumed by an animal, allowing the fasciola to access the mammals liver

What does Schistosoma (blood fluke) cause?

Infection called schistosomiasis, which leads to severe anemia

What is the intermediate host for schistosoma?

Snail

How does the cercariae schistosoma get to the definitive host?

It burrows through skin or by drinking water

Tapeworms have

A degenerate digestive system and nervous systems and a highly developed reproductive system

What is a benefit of tapeworms being flat?

It enhances diffusion so that there is no need for respiratory and circulatory systems

How do tapeworms attach to the host?

Scolex

What are the segments called on a tapeworms body?

Proglottids, which contain both male and female reproductive organs

Phylum Nematoda (roundworms) traits

Long cylindrical bodies, usually tapered at both ends, covered with a tough cuticle

What kind of symmetry do nematoda have?

Bilateral symmetry

How do roundworms differ from flatworms?

They have a complete digestive system with a mouth/anus

Roundworms are triploblastic, what are the 3 layers of definite tissue?

Ectoderm, mesoderm, endoderm

What are nematoda organs suspended in?

Pseudocoelom