A guide to the deep-water sponges of - NMFS Scientific Publications ...

69. Myxilla (Ectyomyxilla) parasitica Lambe, 1893
Description. This sponge is encrusting, typically on
the shells of scallops (Chlamys sp.). Surface is finely
structured with radiating canals leading to small oscula
that are flush with the surface. Thin encrustation is
less than 1 cm in height and typically covers the entire
available shell surface. Color in life is light brown to
golden brown.
Skeletal structure. Ectosomal tornotes have unequal
ends and mammillate projections at these ends (160–
186 × 7–9 µm). Choanosomal acanthostyles are in an irregular
meshwork (208–310 × 10–15 µm); microscleres
are large isochelae (52–65 µm), small isochelae (15–20
µm), and thin sigmata (17–25 µm).
Zoogeographic distribution. Locally abundant in the
North Pacific Ocean. In Alaska – central Aleutian Islands.
Elsewhere – Bering Sea (Russia), Sea of Okhotsk
(near the Kuril Islands) and British Columbia (near
Vancouver Island).
Habitat. In Alaska – encrusts scallop shells at depths
between 98 and 250 m. Elsewhere – on rocks, pebbles,
and sand at depths between 15 and 126 m.
Remarks. They are often very abundant in scallop
beds.
Photos. 1) Specimen collected at a depth of 138 m
in the central Aleutian Islands. Specimen completely
encrusts a scallop (Chlamys sp.). Grid marks are 1 cm 2 .
2) Specimen (center) collected at a depth of 98 m in
the central Aleutian Islands. 3) A bed of scallops (Chlamys
sp.), almost all of which are completed encrusted
with Myxilla parasitica. The gorgonian Fanellia fraseri is
at center.
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