Animals having single opening for mouth and anus is:

Question

Accepted Answer

The correct option is 3:

Fasciola, commonly known as the liver fluke, is a parasitic flatworm belonging to the phylum Platyhelminthes. A characteristic feature of flatworms, including Fasciola, is their incomplete digestive system. This means they possess a single opening that functions as both the mouth for ingestion of food and the anus for egestion of undigested waste. Their digestive tract is typically a blind sac, meaning it has only one opening. This simple digestive system is a primitive trait in the animal kingdom, often associated with their parasitic lifestyle where they absorb nutrients directly from their host, and their food source is typically pre-digested.

The incorrect option is 1: Asterias. Asterias, or starfish, belong to the phylum Echinodermata. Echinoderms have a complete digestive system with separate mouth and anus. In the case of starfish, the mouth is typically on the oral (underside) surface and the anus is on the aboral (upper) surface.

The incorrect option is 2: Ascidia. Ascidia is a genus of ascidian, commonly known as sea squirts, which are tunicates belonging to the phylum Chordata. Tunicates, even though simple in form, possess a complete digestive system with distinct openings for mouth and anus. They are filter feeders, and water enters through an incurrent siphon and exits through an excurrent siphon, with food being processed through a complete digestive tract.

The incorrect option is 4: Octopus. Octopuses are highly evolved cephalopods belonging to the phylum Mollusca. They have a well-developed and complete digestive system with a distinct mouth, esophagus, stomach, intestine, and anus. Their anus is typically located within the mantle cavity, through which waste is expelled.