Question

Water flea is the common name of
(a) Dragon fly
(b) Prawn
(c) Cyclops
(d) Daphnia

Answer 1

Hint: The planktonic crustaceans belonging to the Phyllopoda (sometimes referred to as Branchiopoda) are distinguished by flattened leaf-like legs used by the filtering apparatus to create a water current. Daphnia belongs to the Cladocera, within the brachiopods, whose bodies are covered by an uncalcified shell known as a carapace.

Complete answer:
Daphnia is usually referred to as the water flea because its form of salt swimming resembles flea movements. Daphnia is a member of the Cladocera order of the Arthropoda phylum. They are small, planktonic shellfish. They live in diverse marine habitats, ranging from acidic swamps to wetlands, ponds, streams, and rivers with fresh water.

In the water, Daphnia feeds on small, suspended particles. They are feeders (philtre feeders) for suspension. With the assistance of a filtering apparatus consisting of cephalopods, which are flattened leaf-like legs that create a water current, the food is collected. As the current flows anterior to posterior, particles are formed by the Daphnia that is moved by special setae into the food groove. While the feeding apparatus is so effective that it is also possible to capture bacteria, planktonic algae typically make up the food. Green algae are among the best foods, and either Scenedesmus or Chlamydomonas are used in most laboratory experiments, both of which are easy to grow in monoclonal chemostats. Particles from about $1\mu m$ up to $50\mu m$ are typically ingested by Daphnia, while particles up to $70\mu m$ in diameter can be present in large individuals' gut contents.

Additional information:
A dragonfly is an insect belonging to the Anisoptera Infraorder Order Odonata. Wide, multifaceted eyes, two pairs of solid, transparent wings, often with colored patches, and an elongated body characterize adult dragonflies.
The term prawn is used especially for large swimming crustaceans or shrimps in the United Kingdom, Ireland, and Commonwealth countries, particularly those with commercial significance in the fishing industry. Shrimps included in this group also belong to the Dendrobranchiata suborder.
Cyclops are tiny crustaceans, also called water fleas, of the Cyclopidae family. In rural or peri-urban areas, they are typically located in stagnant bodies of freshwater, such as wells and ponds in poor agricultural communities. When they drink water containing infected cyclops, the infection is transferred to humans.
So, the correct answer is ‘(d) Daphnia’.

Note: Although there is no risk to humans or domestic animals, because of their rapid reproduction rates, spiny water fleas may have a huge effect on aquatic life in lakes and ponds. Other than spread prevention, there are no known current management options for infestations.