Nassarius horridus
A spined, small marine snail of the Nassa mud snails.
Nassarius horridus, called the horrid nassa, is a marine gastropod mollusk belonging to the family Nassariidae, which includes the Nassa mud snails and dog whelks. Its shell is small, ranging from 8 to 15 mm in length, and has an ovate, somewhat spherical shape covered in spines. The spire is conical and pointed, made up of six or seven whorls, with the body whorl noticeably larger than the rest. Longitudinal folds run along the spire, each bearing regularly spaced, pointed conical tubercles that match the shell’s overall color. The first row of these spines sits just below the suture, while the last row cuts obliquely across the shell’s base. Between each row of spines, fine, numerous transverse striae are visible. The aperture is white and semilunar, with a thick outer lip lined internally by fine striae. The columella is nearly straight and is covered by the inner lip, which forms a callosity. The shell’s color is uniform, either a white fawn or a pale orange. This species is found off Durban, South Africa; along East Africa; near Madagascar, Réunion, and Aldabra; and across the Indo-West Pacific, including East India, western Thailand, Papua New Guinea, Indonesia, the Philippines, Indo-Malaysia, the Ryukyu Islands, the Solomon Islands, the Marshall Islands, the New Hebrides, New Caledonia, the Loyalty Islands, Fiji, Tonga, the Samoan Islands, and the Caroline Islands. It also occurs off Australia in the Northern Territory, Queensland, and Western Australia.
Quick Facts
- Genus
- Nassarius
- Species
- horridus
Facts from the source article.
Lore & Background
The shell of Nassarius horridus is ornamented with longitudinal folds on the spire, upon which are regularly disposed pointed, conical tubercles of the same color as the rest of the shell. The first row of these spines lies immediately beneath the suture, and the last row obliquely intersects the base of the shell. Between each row of spines, transverse striae, fine and numerous, are observed. The aperture is white and semilunar, with a thick outer lip that bears fine striae internally. The columella is nearly straight and is covered by the inner lip, which forms a callosity. The color is uniform, either white fawn or sometimes pale orange.
This species has a wide distribution across the Indo-West Pacific, occurring off Durban, Republic of South Africa, East Africa, Madagascar, Réunion, Aldabra, East India, Western Thailand, Papua New Guinea, Indonesia, the Philippines, Indo-Malaysia, Ryukyu Islands, Solomon Islands, Marshall Islands, New Hebrides, New Caledonia, Loyalty Islands, Fiji, Tonga, Samoan Islands, Caroline Islands, and off Australia (Northern Territory, Queensland, Western Australia).
Reader's Guide
Nassarius horridus is a representative of the family Nassariidae, a group of mud snails and dog whelks that are common in shallow marine environments. Its small, spined shell, reaching up to 15 mm in length, is notable for the regular arrangement of conical tubercles along longitudinal folds, a feature that distinguishes it from related species. The species was described by Dunker in 1847, with additional early documentation by Quoy and Gaimard in 1833 and Gould in 1850. Later systematic work by Cernohorsky in 1984 placed it within the family Nassariidae, and it has been included in regional guides such as those for Australian marine shells by Wilson in 1994 and for South African seashells by Marais and Kilburn in 2010. Its broad distribution across the Indo-West Pacific, from East Africa to the Pacific islands and Australia, indicates a successful adaptation to tropical and subtropical waters. The species remains a subject of study in malacology, particularly for its shell morphology and geographic range.
Did You Know?
- The shell length of Nassarius horridus varies between 8 mm and 15 mm.
- The shell color is uniform white fawn, sometimes pale orange.
- The outer lip is thick and furnished internally with fine striae.
- This species occurs off Durban, Republic of South Africa, and across the Indo-West Pacific to Australia.
Frequently Asked Questions
What is Nassarius horridus?
Nassarius horridus, commonly called the horrid nassa, is a small marine gastropod mollusk that belongs to the Nassariidae family alongside the familiar Nassa mud snails and dog whelks. Its most eye-catching trait is a shell densely studded with sharp spines, giving it a spiky, almost armored look.
How large does Nassarius horridus get?
Adults of this species measure between 8 and 15 millimeters in shell length, making them a rather modest-sized member of the Nassariidae. Despite their small stature, the heavy spination makes them visually stand out on the seafloor.
What does the shell of Nassarius horridus look like?
The shell has an ovate, slightly spherical form with a conical spire built from six or seven whorls, the body whorl being noticeably the largest. Its coloration is typically a uniform white-fawn, though some specimens carry a pale orange tint, and the semilunar aperture is framed by a thick outer lip bearing fine internal striae.
What makes Nassarius horridus's spines distinctive?
Longitudinal folds run along the spire, each carrying regularly spaced, pointed conical tubercles that match the shell's overall hue. The first row of these spines sits just beneath the suture line, and the consistent, dense arrangement is what earned the species its 'horrid' common name.
Where does Nassarius horridus fit among other nassa snails?
It is classified within the family Nassariidae, the group that encompasses the Nassa mud snails and dog whelks. As a spined, small marine snail, it stands out among its relatives for the density and prominence of its conical tubercles compared to smoother-shelled nassariids.
More in Marine Snails: Ceriths, Nassas and Conchs, Part 2 1-24
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