Phylum Platyhelminthes (Flatworms) in the Christopher B. Smith Preserve

Platyhelminthes Characteristics: Platyhelminthes have bilateral symmetry, and are unsegmented and soft-bodied invertebrates. The body of a flatworm is dorsoventrally flattened. The worm does not have a body cavity that separates its body wall from its digestive tract.

Some members of the phylum are free-living, while others are parasites.

There are four classes in the phylum: 1) Trematoda (flukes), 2) Cestoda (tapeworms), 3) Turbellaria (planarians), and 4) Monogenea (small parasitic flatworms mainly found on skin or gills of fish).

The only member of the phylum that has been found so far in the Christopher B. Smith preserve is a land planarian.

Interactions in the Smith Preserve: A land planarian devours earthworms, slugs, insect larvae, and other planarians. Predators of land planarians include beetles, snails, and other land planarians.

 
Class
Order
Family
Species Name
Common Name
Turbellaria
Tricladida
Geoplanidae
Unknown

 

 

Family Geoplanidae

Unknown Species ... Land Planarian

On November 16, 2021, the webmaster examined fallen branches of an oak tree, that were laying on the floor of a gopher tortoise preserve hammock, south of the pond and just west of the gopher tortoise fence.

Several small land planarians were curled on the bottom of the decomposing, moist wood. Once disturbed, they began crawling. Normally planarians move and feed at night.

Each had longitudinal stripes of tan and brown, a pointed end, and a rounded end. The anterior end was the rounded end.

This planarian is not likely native species. but probably imported as a result of horticultural practices and dispersion of potted plants in commerce. Land planarians lack a respiratory and circulatory system, a skeleton, and an anus. The mouth serves as an anus and is located near the mid-body on the ventral surface.

Reproduction is principally by fragmentation at the posterior end where lateral margins pinch off. The posterior fragment sticks to the substrate and the parent worm pulls away, separating from the fragment. The posterior fragment is capable of movement right away and within a week to 10 days, a pale head begins to form. Another form of reproduction involves bright red eggs being deposited in cocoons. Planarians emerge from the eggs in about three weeks.

 

Return to top

 

 

© Photographs and text by Susan Leach Snyder (Conservancy of Southwest Florida Volunteer), unless otherwise credited above.

Return to Insect Order List

Return to Christopher B. Smith Preserve