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Hammerhead Worm

Bipalium kewense


First time to actually see one of these. It was about 4 cm in length, brown with darker brown stripes down the body. It looks very much like Bipalium kewense, of asian origen. These are land Planarians or flatworms of the family Geoplanidae. There are many species based on the head shape and color pattern. All are carnivorous predators, feeding on earthworms, slugs, insect larvae and other soft soil creatures. They are often referred to as "Immortal" since they can regenerate body parts as well as regenerate themselves from a single body part or section. They have both sexual and asexual reproduction, the latter being the most common. If this is B. kewense, 4 cm is very small. They are known to reach 20 cm or more. They have a peculiar method of movement, using a "creeping sole" of cilia which moves over a thick secretion of mucous. Some is visible in the 2nd picture. Since it was on a cement driveway, I decided to move it to a moist soil environment. It was really difficult to pick up, even with forceps. The mucous is incredibly thick and sticky, much more so than that of a snail or slug.


Found at night, semi-rural residential area, San Cristobal de Las Casas, Chiapas, Mexico, 2,200 meters.


1 Species ID Suggestions

Tukup 4 years ago
Hammerhead Flatworm/Arrowhead Flatworm
Bipalium kewense Bipalium - Wikipedia

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LaurenZarate 4 years ago

Thank you Tukup, I agree, it does look most like B. kewense.

Tukup 4 years ago

Hi Lauren. Nice fotos. The ID suggestion is from the box showing the heads of six Bipalium <> Based on the coloration, I believe it is B. kewense. Thanks for sharing these fotos.

Mark Ridgway
Mark Ridgway 4 years ago

A must to admire.

Neil Ross
Neil Ross 4 years ago

What an incredible species. If I had the power to regenerate myself, it would be the 30 years younger me! :) Excellent spotting, Lauren. Great info and photos too.

Spotted by

San Cristóbal de las Casas, Chiapas, Mexico

Spotted on Jul 12, 2019
Submitted on Jul 21, 2019

Spotted for Mission

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