Do planarians have a digestive system?
Most flatworms, such as the planarian shown in Figure 1, have a gastrovascular cavity rather than a complete digestive system. In such animals, the “mouth” is also used to expel waste materials from the digestive system. Some species also have an anal opening. The gut may be a simple sac or highly branched.
What sensory organs do flatworms have?
They have a central nervous system containing a brain and a nerve cord. Clusters of light-sensitive cells on either side of their head make up what are called eyespots. The head region of the flatworm has other paired sense organs connected to the flatworm’s simple brain.
Does the Planaria have a complete or incomplete digestive system?
Figure 1: This planarian is a free-living flatworm that has an incomplete digestive system, an excretory system with a network of tubules throughout the body, and a nervous system made up of nerve cords running the length of the body with a concentration of nerves and photosensory and chemosensory cells at the anterior …
What specific structures allow a planarian to sense food or other chemicals where on its body are these structures?
Planarians can sense and respond to chemical stimuli in their environment by using chemoreceptors mainly localized on the sides of their bodies (auricles). Their bodies also contain structures called protonephridia, which function like kidneys by removing fluid waste and regulating salts and water intake.
What are the different sense organs present in planaria and give their functions?
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.
How does Planaria sense the presence of food?
Planaria senses the presence of food by tasting the water around it for compounds released by nearby food using its auricles which are chemoreceptors. Planarians lack specialized gas exchange organs. Hydra can chemically sense the presence of food in water and also sense food by vibrations.
What is the sense organ in planaria?
How many types of nervous systems and sense organs are found in flatworms?
Flatworms of the phylum Platyhelminthes have both a central nervous system (CNS), made up of a small “brain” and two nerve cords, and a peripheral nervous system (PNS) containing a system of nerves that extend throughout the body.
Why do scientists say Planaria have ladder like organs?
They can reproduce asexually simply by pinching in half; each half grows a new half. Scientists say planaria have ladder like organs. Why? It consists of a brain and nerve cords arranged in a ladder-like configuration.
What specific structures allow a planarian to sense light where on its body are these structures?
Planarians have ocelli (eyespots) allow the presence and intensity of light to be determined. These structures are covered but have an opening to one side and forward. They can tell the direction of light because shadows fall on some of the receptor cells while others are illuminated.
What organs are located in the head of Planaria?
Planarians have a head region with sense organs. The nervous system of Dugesia is somewhat more complex than the nerve net of Cnidarians. It consists of a brain and nerve cords arranged in a ladder-like configuration. Planarians have ocelli (eyespots) allow the presence and intensity of light to be determined.
Do flatworms have sense organs?
Flatworms have prominent eyespots. These constitute the flatworm’s most prominent sensory organs. However, while the eyespots resemble eyes, the organs are much more simple. Instead, the eyespots can only tell light from dark.
Does a planarian have an one way digestive system?
Unlike other worms, planarians have a two-way digestive tract . Food enters the mouth and is digested in the intestine; the nutrients diffuse throughout the body (there are no circulatory or respiratory systems). The undigested materials are discharged from the mouth (there is no anus).
Do Planaria have immune systems?
Planarian , a representative of platyhelminthes , has strong regeneration ability and less complicated innate immune system. However, planarian immune system remains poorly understood. In this paper, a novel C-type lectin-like protein, namely, DjCTL was identified and characterized in Dugesia japonica.
Do planarians have a nervous system?
Planarians are non-parasitic worms of the turbellaria class. Their nervous system consists of a cerebral ganglia under the eyespots in the head. This ganglia is sometimes considered a brain, because it has been shown to electric activity similar to that of other animals. From the ganglion are two nerve cords that extend to the tail.
Does a planarian have a body cavity?
Planaria have 3 germ layers ( ectoderm , mesoderm , and endoderm), but lack a body cavity or coelom. They have a single-opening digestive tract, consisting of one anterior branch and two posterior branches in freshwater planarians.