Home Acknowledgments Conventions Glossary Maps References Links Articles Thumbnails Species list Family Next species _______________   Additional Photos   detail   orange    young, white?   deep water   in cave   feeding     egg mass	Umbraculum umbraculum (Lightfoot, 1786)   Maximum size:  about 127 mm (Hoover, 2006). Identification:  This is a large species with a broad, cap-shaped external shell covering the center of the notum. The mantle is covered with large, relatively complex tubercles and its color varies from white through orange to dark brown, usually with contrasting lighter pigment of the tips of the tubercles. Very young animals may have less well developed tubercles. Shells of shallow water animals are usually overgrown with algae and remnants of a hairy periostracum may be present around their margins. Its shell is more heavily calcified than the shell of Umbraculum sp. #1. Natural history:  Umbraculum umbraculum is a moderately rare nocturnal species found in moderately exposed to highly exposed rocky habitats. It occurs in tide pools and to depths of at least 162 m (532 ft). The record depth is based on photographs taken from HURL submersibles. It feeds on sponges and lays large, frilly white egg masses. Distribution:  Big Island, Maui, Oahu and Midway: widely distributed in the Indo-Pacific. Taxonomic notes:  This is the species that Kay, 1979 lists as Umbraculum sinicum (Gmelin, 1791). Some authors list the Atlantic population as a separate species, Umbraculum mediterraneum (Lamarck, 1819) and it seems likely that both the Atlantic population and the eastern Pacific population will ultimately be recognized as distinct based on consistent differences in tubercles, shell calcification and color. It's referred to as the "umbrella slug" in Hoover, 1998 & 2006 and was probably first reported from Hawaii in Pease, 1868. (Note 1) Photo:  CP: 94 mm; found by student; tide pool, Napili Bay, Maui; Sept. 8, 1995. Observations and comments: Note 1:  Although based on a small sample size, the tubercles of the orange and brown forms appear to be consistently different. In the orange form, the compound tubercles are broader and more irregular in size with few secondary tubercles (or only wrinkled tissue) between them. In contrast, the compound tubercles in the brown form are narrower, more conical, more even in size and have tall evenly spaced secondary tubercles between them. For that reason, it's conceivable that the two could ultimately turn out to be separate species when their DNA is checked. The pattern in the orange form is typical of the species elsewhere in the Indo-Pacific. So, if split, it would probably retain the name with the brown form potentially being a Hawaiian endemic. Occasional animals lack the orange background of the orange form but retain its tubercle pattern (while also lacking the well-defined brown background of the brown form). Comparable animals occur in Japan and elsewhere.
	Thumbnails Species list Family Next species Top