Animal Profiles
Worms

Flatworm

Platyhelminthes

Living

Living individuals or members of this group exist today. This does not mean they are safe from extinction.

Flatworms include many unrelated-looking forms. This account describes the freshwater planarian Girardia tigrina, called Dugesia tigrina in the cited source.

Two Girardia tigrina flatworms in a Petri dish, photographed after collection from a pond.

Two Girardia tigrina flatworms in a Petri dish, photographed after collection from a pond.

Filet 123 · CC BY-SA

At a glance

Location
This planarian inhabits ponds, lakes and streams in North America.
Habitat
Rivers and lakes
Diet
Carnivore
Food
Small invertebrates, including insect larvae and crustaceans, provide food.

Classification

Common name
Flatworm
Browse group
Worms
Scientific name or taxon
Platyhelminthes
Taxon rank
phylum

Taxonomy checked against GBIF. For breeds and hybrids, this describes the listed parent taxon.

Three things to know

  • It is a free-living flatworm.
  • Paired eyespots occur on the head.
  • Cilia help it glide.

Habitat and range

This planarian inhabits ponds, lakes and streams in North America. It shelters beneath stones, vegetation and other submerged debris; introduced populations also occur outside its native range.

Appearance and adaptations

The soft body is flattened from top to bottom, with a roughly triangular head and paired eyespots. Tiny surface cilia and mucus help it glide over submerged surfaces.

Diet and behaviour

Small invertebrates, including insect larvae and crustaceans, provide food. Mucus assists movement and prey capture. This free-living predator differs from the parasitic flatworms included in the wider phylum.

Sources

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