Mollusks

The 2023 Live Mollusk Count

On Sunday, January 22, volunteers and staff from the National Shell Museum and the Sanibel-Captiva Conservation Foundation completed the 2023 Live Mollusk Count. The count took place along the Gulf side on the eastern end of Sanibel Island, at low tide, including 27 participants. National Shell Museum Science Director & Curator José H. Leal observed that “the 2023 Shell Count achieved very good results. The number of participants, methods, and count area lend themselves to comparisons with the J

Shell of the Week: The Eared Ark

Anadara notabilis (Röding, 1798), reaches 92 mm (about 3.6 inches). Its shell valves have about 25 to 27 radial ribs per whorl, with fine commarginal (“concentric”) lines cross the ribs, giving a beaded aspect to the valves in this species. The shell is white and the periostracum, when present, is brown and heavy (but not as heavy as in the Ponderous Ark, Noetia ponderosa. This species occurs in shallow water along the coast of East Florida and the northern coast of the Gulf of Mexico, but is no

Three New Nautilus Species!

Exciting news in the world of mollusks, with the recent description (the research article was published yesterday, January 25, 2023) by Gregory J. Barord and his collaborators of three new species of Nautilus. The three species occur respectively off American Samoa (Nautilus samoaensis), Fiji (N. vitiensis), and Vanuatu (N. vanuatuensis), all in the Southwest Pacific Ocean. The authors used contemporary techniques to define the new species, including evidence from shell and body anatomy, all val

A Little Sea Slug from Sarasota

This small (about 11 mm, or about 0.5 inch) but endearing sea slug was originally identified as Flabellina dushia. It has a bluish-white, slightly translucent body with reddish cerata. The cerata contain expansions of the digestive tract that are used in some species to store the stinging cells of animals they eat such as sea anemones, hydroids, and sea fans. Not only the sea slugs can inhibit the action of stinging cells, but they also recycle the cells for their own defense. This slug was phot

Shell of the Week: The Mottled Miter

Vexillum dermestinumLamarck, 1811 reaches about 17 mm (about 0.7 inch). The shell sculpture includes well-defined axial ribs and narrower spiral ridges. The columella has three strong, beaded folds. This species has a complex color pattern of brown bands and spots on a white and yellow background. The Mottled Miter occurs in the east coast of Florida and the Keys, Gulf of Mexico, the Caribbean all the way to the tropical part of Brazil, but is not found in Southwest Florida. #vexillumdermestinum

Complex Vision in Strawberry Conchs

True conchs in the family Strombidae have large, camera-type eyes that are extra well-developed and more complex when compared to the eyes of other gastropods. In Strawberry Conchs, Conomurex luhuanus, the eye contains a hemispherical lens, a cornea, a pupil surrounded by a pigmented iris, a vitreous body, and a cup-shaped retina consisting of several layers. The eye is very large in relation to body size and is very sophisticated, even when compared with those of other true conch species. Resea

Shell of the Week: The Florida Slender Chiton

Chitons are mollusks with eight (sometimes seven) shelly plates called valves. The Florida Slender Chiton, Stenoplax floridana Pilsbry, 1892 reaches about 38 mm (1.5 inches) and is about three times as long as it is wide. The central areas of valves bear strongly beaded longitudinal ribs, and the end valves have concentrically arranged beads. Its color can be whitish to whitish-green, with markings of darker green or gray This species is not uncommon in the coral reef habitats of South Florida a

Shell of the Week: The Digitate Thorny Oyster

Reaching about 70 mm in size, Spondylus tenuis Schreibers, 1793, is one of the few species of thorny oysters (family Spondylidae) found in the western Atlantic. Its shell comes in varied colors, including rusty brown, brick red, orange, cream-yellow, whitish, or variations of these hues. The sculpture consists of flat or pointy spines that are longer toward the edge of the shell. The lower valve is almost always cemented to a hard surface, such as rocks, ship wrecks, or oil platforms, but someti

Meet the Comb Bittersweet!

Tucetona pectinata (Gmelin, 1791) is the most common out of two locally found species of the bittersweet family, the Glycymerididae. Its shell may reach 30 mm (about 1.2 inches), and is circular, with a sculpture of 20–35 relatively wide ribs that are flat in cross-section. As the image above shows, the ribs are overlaid with a microscopic sculpture of regularly spaced, commarginal (“concentric”) threads. The shell hinge (below) has about 20–24 small “teeth” that ensure that the shell valves clo

Shell of the Week: The Dubious Cerith

At about 4.5 mm (about 0.5 inch) in height, the Dubious Cerith, Finella dubia (d’Orbigny, 1840) is one of the small gastropod species that dwell in sea grass beds around Southwest Florida and other parts of the tropical Western Atlantic. Dubious Ceriths feed on plant and algal detritus. The shell is elongate, turret-shaped, with three or more strong spiral cords. The shell color may be cream-white to light-brown with faint spots of darker color. #finelladubia #dubiouscerih #scaliolidae #sanibeli