Stalked Tunicate, Monterey stalked tunicate, Long-stalked sea squirt
|Styela montereyensis observed at Cape Flattery, Wa 11 cm in length|
|Photo taken by Brandon White 7/08/02|
How to Distinguish from Similar Species: Can be easily confused with Styela clava. It can be distinguished by the facts that Styela clava has the following (a) tunic usually bearing conspicuous tubercles, (b) tunic often with irregular longitudinal wrinkles but never with regular ridges and grooves along entire body representing thick and thin regions of test, and (c) both siphons straight, the oral siphon not recurved toward base of stalk.
Geographical Range: Vancouver Island to Baja, California.
Depth Range: Low intertidal zone to about 30m
Habitat: Fairly Common, firmly attached to solid substrata in calm to very rough waters. In the Pacific Northwest it is mainly found in the outer Straits and open coast, but rarely in inland waters.
Biology/Natural History: Although
they just look like slimy sacs, tunicates or sea squirts, are more closely
related to humans than any other invertebrate group. This is because larval
tunicates have several chordate structures - including a nerve chord and
a notochord. These are later lost in most adult forms. Two openings are
found on the tunicate: the buccal siphon (water comes in) and the atrial
siphon (water goes out). Sea squirts got their name because a gentle squeeze
will cause water to shoot out of their atrial siphon! The sedentary adult
forms can either be solitary or colonial. A cool fact about tunicates is
that they have a long, tubular heart that contracts in two directions!
Breeding and larval settlement occur in the summer. Study of the developing eggs shows that the inner follicle of the oocyte provides the test cells that are enclosed with the ovum inside the chorion. Both eggs and sperm are shed to the sea. In natural situations the larvae settle best on surfaces that have been underwater at least several months. In metamorphosing larvae the tail collapses, as is characteristic in members of the suborder Stolidobranchia, by contracting of the notochord itself, not (as in Aplousobranchia) by contraction of the caudal epidermis This species may store vanadium (to about 36-40 ppm dry weight) in its tunic. On the open coasts of Washington and Vancouver Island this species often has the copepod Pygdelphys aquilonaris in its branchial sac.
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Brown and Rovetta, 1996
Brusca and Brusca, 1978
Morris et al., 1980
Ricketts et al., 1985
The name Styela means "pillar".
An individual from San Simeon, CA. Photo by Dave Cowles, April 1997
This individual is under a rock at Cape Flattery. Photo by Dave Cowles, July 2005