What is the structure of a flatworm?

They are bilaterally symmetrical (i.e., the right and left sides are similar) and lack specialized respiratory, skeletal, and circulatory systems; no body cavity (coelom) is present. The body is not segmented; spongy connective tissue (mesenchyme) constitutes the so-called parenchyma and fills the space between organs.

Is planaria a flatworm?

planarian, (class Turbellaria), any of a group of widely distributed, mostly free-living flatworms of the class Turbellaria (phylum Platyhelminthes). Planaria is the name of one genus, but the name planarian is used to designate any member of the family Planariidae and related families.

How are planarians different from other flatworms?

The key difference between planarians and tapeworms is that planarians are unsegmented free-living flatworms of the class turbellaria that live on freshwater. Meanwhile, tapeworms are segmented parasitic flatworms of the class Cestoda which reside on the intestines of animals including humans.

What sensory structures does a planarian have at its anterior end?

Additionally, the planarian has two visible sensory organs. The auricles are lateral flaps near the anterior of the animal. The auricles are chemoreceptors and sense chemicals in the water. Also near the anterior are two eyespots.

What is the alimentary canal of Planaria?

The planarian has very simple organ systems. The digestive system consists of a mouth, pharynx, and a gastrovascular cavity. The mouth is located in the middle of the underside of the body. Digestive enzymes are secreted from the mouth to begin external digestion.

Is Planaria a microorganism?

Planarians (Platyhelminthes)—An Emerging Model Organism for Investigating Innate Immune Mechanisms. An organism responds to the invading pathogens such as bacteria, viruses, protozoans, and fungi by engaging innate and adaptive immune system, which functions by activating various signal transduction pathways.

What is the shape of the planarian?

The planarian has a soft, flat, wedge-shaped body that may be black, brown, blue, gray, or white. The blunt, triangular head has two ocelli (eyespots), pigmented areas that are sensitive to light.

What are the characteristics of planaria?

The spade-shaped head has two eyes and sometimes auricles. The tail is pointed. Planaria have three germ cell layers (i.e., ectoderm, mesoderm, and endoderm), which are the same as humans. They have a solid body with no body cavity (referred to as acoelomate).

How do planaria breathe?

The planarian does not have gills or lungs, it obtains its oxygen by simple diffusion over its flat body. The dugesia cannot survive outside of the water, so biologists studying it must make sure that the specimen has plenty of water that is aerated.

What is the structure that has the mouth of the planaria?

The planarian has very simple organ systems. The digestive system consists of a mouth, pharynx, and a structure called a gastrovascular cavity. The mouth is located in the center of the underside of the body.

What is the characteristics of planaria?