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Common Name: The Tiger Flatworm

Scientific Name: Pseudoceros crozieri

Kingdom: Animalia

Phylum: Turbellaria

Class: Turbellaria

Order: Polycladida

Family: Pseudoceritidae

Genus: Pseudoceros

Species: P. crozieri

The Pseudoceros crozieri, or Tiger Flatworm, is identified for it's tiger-like stripes and coloration. On the surface of the dorsal, wavy black or dark brown stripes line the organism laterally from the center to the edge, and often end in a black dot. The body color of the organism can be; white, green, or even orange due to chemical compounds absorbed from eating ascidians. The lining of the flatworm's body is lined with marginal ruffles, and the amount of ruffles depends on the size of the organism. They are generally small, usually growing up to 40mm, and are found in colonies of it's prey, the orange tunicate.


The epidermis is lined with thousands of cilia, and both inner and outer muscles, which help to structure the animal. To also help with body structure, the flatworm has a hydrostatic skeleton. The habitat of the Pseudoceros crozieri, can be found in most tropical waters, leading from South Carolina to Florida, and also throughout the the Carribean and Bermuda Sea. These colonies can be found near mangrove tunicates, near the mangrove roots and any other hard substrates in shallow, intertidal or subtidal waters.


Tiger Flatworms, feed strictly on orange tunicates. They feed by inserting is pharynx into the zooid of the tunicate and secretes proteases for external digestion. It then sucks the digested parts from the test of the tunicate.


Tiger Flatworms are simultaneous hermaphrodites. They mate quite frequently, and usually do it through hypodermic insemination. To find a mate, the flatworm relies on chemical compounds, which can sense using their large pseudotentacles. Hypodermic isemination occurs when two individuals insert each other with their copulatory stylets. Then, sperm is transferred between the individuals bilaterally in bundles. The sperm bundles travel up the parenchyma to the oviducts and fertilize the eggs, which are then set down in egg masses. In approximatley 10 days. The Tiger Flatworm, can also asexually reproduce through fission. If an individual divides into two parts, it can regenerate itself.

Author: Taighler R.

Published: 05/2008

Sources: Pseudoceroscrozieri.html

Photo Credit: © Copyright Marian K. Litvaitis, University of New Hampshire, 2005-2007

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