Land planarian

Bipalium pennsylvanicum

ORDER

Tricladida

FAMILY

Bipaliidae

TAXONOMY

Bipalium pennsylvanicum Ogren, 1987, Pennsylvania, United States.

OTHER COMMON NAMES

None known.

PHYSICAL CHARACTERISTICS

Long, brownish yellow in color with three dorsal stripes; head is half-rounded or lunate, body retracted and coiled on self at rest, during locomotion over a flat dry surface, the body is greatly extended, undulates, and head is raised above surface moving from side to side; head bordered by numerous, small eyes that extend posteriorly along the body; mouth with eversible pharynx located in mid-region of body; gonopore is just posterior to mouth.

DISTRIBUTION

Considered to be introduced into United States, it has only been found in Pennsylvania in outdoor habitats, though other species occur throughout eastern United States.

HABITAT

Lives in damp areas under stones and pieces of wood and are capable of over-wintering in soil where air temperatures reach freezing.

BEHAVIOR

During day, it remains in damp, dark areas under rocks and wood, and in soil. Under dry conditions, it may move further into soil to find favorable conditions.

FEEDING ECOLOGY AND DIET

It captures earthworms by attaching ventral side of head and tail. Thrashing by prey results in planarian getting a better grasp on prey. Arthropods and mollusks are not preferred foods; slugs were only eaten if they were torn open first.

REPRODUCTIVE BIOLOGY

No evidence for fragmentation, but it can regenerate if damaged. After mating, a cream-colored swelling is apparent in mid-region of body where cocoon is developing. Cocoons are yellowish when first deposited and change to light red and eventually shiny black and measure 0.13 in (3.3 mm). One to three juveniles hatch from each cocoon. Juveniles are grayish and lack stripes. It may take 100 days to reach adult size.

CONSERVATION STATUS

Not threatened.

SIGNIFICANCE TO HUMANS

None known.