giant flatworm has
a band of eyespots along the entire margin of the body (may not be
except in transmitted light), plus on its pair of short, blunt nuchal
at the bases of
the tentacles, and in the region of the brain. Its gut
the multi-branching polyclad pattern. The color is tan with
spots or streaks of dark brown dorsally, lighter tan with few if any
Has no suckers
on the ventral surface.
Kaburakia excelsa Bock,
Common name(s) Giant flatworm, Giant
|Kaburakia excelsa, about 9 cm
long. Found under a rock
on Sares Head, Rosario Bay
|(Photo by: Dave Cowles,
How to Distinguish from
Similar Species: This
species if far larger than any other species in this area, and is one
the largest in the world. Most other flatworms in this area
to only about 3 cm long. Polyclads are the only group of
in our area that get larger than microscopic size.
Range: Sitka, Alaska
to Newport Harbor, CA
Depth Range: Mid-intertidal
mussels and under rocks,
sometimes on pilings or on boat bottoms among fouling organisms.
History: The tentacles
are just in front of the brain and can be retracted. This
is negatively phototactic. The margins of the body wrinkle as
animal moves (see photo above). Will eat mussel tissue in the
In Washington, gravid individuals can be found in March.
golden yellow eggs are laid individually in capsules, in a tight-packed
monolayer or bilayer on rocks.
and O'Clair, 1998
et al., 1980
General Notes and
Observations: Locations, abundances,
unusual behaviors, etc.:
This species is
uncommon. In many summers of
intertidal study I have found only one and a colleague had found none.
This photo of the anterior end as the animal tries to climb the side
of the bowl shows the nuchal
tentacles and the dorsal and ventral pigmentation.
Authors and Editors of Page:
Dave Cowles (2004): Created original page