This animal is NOT a crustacean.
As a chelicerate, it has chelicerae
instead of jaws. This species has legs which are longer than
combined length of the proboscis
and trunk. The general outline of the animal is
has both chelicerae
Both sexes have an ovigerous
pair of legs (photo)
(though as in pycnogonids
in general, it is the male which carries the eggs). The chelicerae
are reduced to a knob or tubercle,
and are small and hard to see. The pedipalps
have 6 or fewer articles.
The body is not covered with setae.
about twice as long as its diameter at the base, and is rounded at the
tip (does not taper to a conical point). The lateral
from the trunk are not large (in many other species there are obvious
swellings of the trunk at the base of each pair of legs).
Tanystylum occidentalis (Cole,
Common name(s): Sea spider,
|Tanystylum occidentalis from
an intertidal rock near the
S end of Lopez Island. Total leg span about 8 mm.
|(Photo by: Dave
How to Distinguish
spp have a proboscis
which is at least 3x as long as its diameter at the base and tapers to
a conical point. T. anthomasti is covered
and is usually associated with Gersemia rubriformis.
other species have well-developed chelicerae.
We found it under a rock
in the intertidal.
and Carlton, 1975
General Notes and
Observations: Locations, abundances,
In this closeup view one can see the tiny turretlike head with 4 eyes
(near the left end of the body, between the left (front) pair of
much larger than the head and extends to the left of the body.
Here is an even closer view of the turret-like head, which appears
as a small tubercle
covered with 4 eyes, and also of the proboscis
In this ventral view, the small ovigerous
legs can be seen on the underside of the first body segment (left side,
just to the right of the proboscis).
Here the animal is extending its other, walking legs upward and away
the camera. The proboscis
is to the left. Females of some families lack ovigerous
legs and in other families they are reduced in females.
Pycnogonids are frequently found clinging to hydroids, as here on the
hydroid Aglaophenia sp.
Authors and Editors of Page:
Dave Cowles (2006): Created original page