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

124 Professional Paper NMFS 12
103. Hymeniacidon assimilis Levinsen, 1887
Description. This sponge is polymorphic; massivelobate,
massively cylindrical, ramified, semiglobular, or
even encrusting. Some Aleutian specimens are highly
ramified with some branches coalesced together. Rows
of small oscula are visible in situ. The consistency is
only slightly elastic, stiff, and easily torn. It appears to
be particularly fragile. Height of highly ramified form
is to 1 m or more. Color in life is yellow, light brown,
golden-brown or creamy-white.
Skeletal structure. Ectosomal spicules are tangentially
arranged without further orientation. There is
choanosomal reticulation of polyspicular tracts and
in other parts short tracts and single spicules without
orientation. Styles (135–560 × 6–23 µm) probably occur
in two size categories.
Zoogeographic distribution. Cosmopolitan and locally
common. In Alaska – central Aleutian Islands,
Bering Sea, and Chukchi Sea. Elsewhere – North Pacific
Ocean (Sea of Okhotsk and Sea of Japan), Arctic Ocean
(Barents Sea, East Siberian Sea, and Kara Sea), and
North Atlantic Ocean.
Habitat. In Alaska – attached to cobbles at depths
between 119 and 253 m; also encrusts the gorgonian
Muriceides nigra. Elsewhere – reported at depths between
15 and 110 m.
Photos. 1) Partial specimen (ramified form) collected
at a depth of 119 m in the central Aleutian Islands.
Grid marks are 1 cm 2 . 2) Same specimen as in photo
1 (center) in situ. 3) Close-up view of same specimen
as in photos 1 and 2 showing rows of small oscula.
4) Fragment of specimen (encrusting form) collected
at a depth of 160 m in the central Aleutian Islands.
Specimen encrusts the gorgonian Muriceides nigra.