Dalyellia (Platyhelminthes) Videos

Dalyellia belongs to the order Rhabdocoela, a highly diverse group of flatworms, or turbellarians. Members of Rhabdocoela are simple organisms, having either a simple sac-like intestine or no intestine. A microturbellarian genus, most species of Dalyellia are less than one millimeter in length, although some can reach several millimeters.

The turbellarian body is elongated, relatively soft, and usually tapered at both ends. As a rule, turbellarians are hermaphroditic. In most species, miniature replicas of the adult hatch directly from eggs; these juveniles differ from adults chiefly by the absence of reproductive systems. Asexual reproduction is by means of paratomy, reproduction in which new organs are developed before the animal divides into two or more parts, is common in several genera of microturbellaria.

Turbellarians are common and numerous in freshwater habitats. Freshwater turbellarians are largely free-living organisms, although some freshwater species are ectoparasitic on crustaceans and turtles and some species live symbiotically within the bodies of larger organisms. They can be found in various aquatic systems such as ponds, lakes, streams, ditches, and temporary puddles. However, some may be found in less typical aquatic habitats, such as water films among fallen leaves in a forest or in capillary soil water of a grassy meadow.