What allows the planarian to feed?

Feed planarians once a week. Suitable foods include fresh beef liver, hard-boiled egg yolk, Lumbriculus, pieces of earthworm, crushed aquarium snails, etc. For up to 50 planarians, feed a pea-sized portion. After 30 minutes, transfer the planaria to a fresh container of spring water.

How does the planarian respond to food?

Chemotaxis is a response to a chemical stimulus. Planarians use chemoreceptors to locate food. They move either toward or away from concentrations of dissolved chemicals associated with food.

How do eyespots help planaria?

Planarian flatworms, which often live in dark, watery environments shielded from direct light, don’t have complex eyes like we do. But many do have two lensless, primitive “eyespots” on their heads that can detect the intensity of light.

Is planaria unicellular or multicellular?

Planaria are a type of flatworm belonging to the phylum Platyhelminthes. They are one of the simplest types of multicellular animals.

Why are platyhelminthes more advanced than cnidarians?

Flatworms are more complex than cnidarians. Cnidarians have two layers of cells, the ectoderm and the endoderm; flatworms have a middle layer called the mesoderm between the other two layers (Fig. 3.16).

What is the function of the scolex in a cestoda?

The head, or scolex, bears suckers and often hooks, which are used for attachment to the host. The body covering is a tough cuticle, through which food is absorbed. There is neither a mouth nor a digestive tract. Tapeworms also lack a circulatory system…

How do planaria protect themselves?

Parasitic flatworms protect themselves from the hosts’ digestive liquids by developing teguments or coverings around their bodies.

How are planaria multicellular?

Planarians are simple multicellular animals known as flatworms. They can regenerate parts of their bodies using adult stem cells called neoblasts. When part of a planarian is cut off, its neoblasts multiply to make more stem cells.

What is the function of auricles in a planarian?

These projections are called auricles. They don’t play a role in hearing as their name might suggest but instead contain chemoreceptors to detect chemicals. They are also sensitive to touch. The auricles help a planarian to find food. A planarian’s mouth is located about half way down the underside of its body.

Do Planaria have ears?

Some planaria have two ear-like structures, called auricles, on their heads. Auricles can’t hear the sound but can sense touch. [In this image] A brown speckled planarian ( Dugesia tigrine ). You can see two eyespots and auricles on its head. Planaria are small, but not simple.

How does a planarian eat?

Planarian eats by sucking up food (could be live or dead small animals) with its muscular mouth. Food passes from the mouth through the pharynx into the intestines where it is digested by digestive enzymes. Then its nutrients diffuse to the rest of the planarian through the branches of the gastrovascular cavity.

What is the function of the pharynx in planaria?

The pharynx connects the mouth to the gastrovascular cavity. This structure branches throughout the body allowing nutrients from food to reach all extremities. Planaria eat living or dead small animals that they suck up with their muscular mouths.