Mollusks

The Meta Keyhole Limpet

The Meta Keyhole Limpet, Diodora meta (Ihering, 1927), is a locally rare and elusive gastropod, also found in other parts of the Gulf of Mexico and of the western Atlantic Ocean. Its shell measures about 12 mm (0.5 inch), and has a roundish “keyhole” orifice that distinguishes the species from others in the area. Keyhole Limpets cling to hard surfaces; the orifice helps redirect water containing body wastes away from the head and gills of the animal. The Shell Museum collection has only two shel

The Atlantic Necklace Turrid

The Atlantic Necklace Turrid, Pilsbryspira monilis (Bartsch & Rehder, 1939), is a predatory gastropod, moderately uncommon on Sanibel and Captiva islands. The species reaches about 15 mm (0.6 inch); the shell is slender, brown, with small white beads forming a spiral “necklace-like” pattern (hence the scientific name of the species, monilis, meaning necklace, or string of beads, in Latin.) The Atlantic Necklace Turrid shell aperture (opening) forms an indentation at its posterior end (photo on

The Giant Tun

The Giant Tun, Tonna galea (Linnaeus, 1758) is a large gastropod, with a shell that may reach in excess of 150 mm (6 inches). The shell globose, with a short spire, and ornamented with around 20 spiral, strong but flat ridges. A thin shell allows ridges to show on its internal surface. The Giant Tun has a broad distribution in tropical and subtropical areas of the world’s ocean. The species includes a long-lasting, free-living (planktonic) larval stage that allows dispersal via currents over lar

The Dall Wentletrap

Dall Wentletrap, Cirsotrema dalli Rehder, 1945, can reach more than 30 mm (about 1.2 inches). It has a chalky shell surface with ribs and a background pattern of spiral cords. In addition, about 2-3 thicker ribs per whorl are present in this species. Species in this genus display an outer shell layer called intritacalx, which easily wears off in older shells. Dall Wentletrap is more commonly found in deeper water. The shell on the left, measuring a little more than an inch, was collected in 201

The Truncatellas

The coast of Southwest Florida hosts two species of the small-sized snail genus Truncatella: The Caribbean Truncatella, Truncatella caribaeensis Reeve, 1842 (maximum size 9 mm, or slightly more than 1/3 inch), and the Beautiful Truncatella, Truncatella pulchella Pfeiffer, 1839 (maximum size 0.65 mm, or about 1/4 inch). Truncatellas derive from marine ancestors but have adapted to live almost completely independently from the marine environment, except for the moment of fertilization, when male m

The Bruised Nassa and its Egg Capsules

I last covered the Bruised Nassa, Nassarius vibex (Say, 1822), in this column on September 4, 2015. On that occasion, I mentioned that the habitats preferred by the species are the sandy-mud and mud flats of the back-bay areas that are so common in our part of the coast. I also mentioned the scavenging feeding habits of the species: Bruised Nassas are like “little vultures,” gathering in large numbers to feed on the dead bodies and remains of small marine creatures. Recently, Museum collaborator

The Pigmy Octopus

Octopuses are shell-less mollusks of the class Cephalopoda. One of the local species is the Pigmy Octopus, Octopus joubini Robson, 1929, a species rarely surpassing 5 inches in size. Given their relatively small size, Pigmy Octopuses are capable of temporarily seeking shelter inside empty shells of large gastropods (e.g., Lightning Whelks, Tulips) or bivalves (e.g., Giant Cockles, Quahogs, Pen Shells). Members of this small species, in particular females guarding their eggs, are known to inflict

The Southern Quahog, Encore

The Southern Quahog, Mercenaria campechiensis (Gmelin, 1791), is a large member of the Venus Clam family Veneridae that may grow to be more than 6 inches in size. This local species was originally covered in my column of August 22, 2014. I decided to write again about this magnificent clam after examining and taking a photo of the hinge of a very large specimen. The hinge represents the main connection between the valves, or halves, of the shell of a bivalve mollusk. It has a number of strongly

The Pitted Baby Bubble

The Pitted Baby Bubble, Japonactaeon punctostriatus (C.B. Adams, 1840), is a local microsnail that reaches about 1/5 inch in size. The shell of the living snail is transparent, becoming opaque after the animal dies, and is ornamented with spiral rows of pin-holes, which are present only on the abapical (“top”) part of the whorls. The juvenile live snail illustrated in the photo on the right was collected on September 15, 2014, by Florida Gulf Coast University (FGCU) student Thomas Behmer on from

The Atlantic Paper Mussel

A member of the Mussel family Mytilidae, the Atlantic Paper Mussel, Arcuatula papyria (Conrad, 1846), is an elusive local species that happens more abundant in nature than its relative obscurity and scarcity in local collections would lead us to believe. One of the reasons for its status as a poorly known species is that it lives burrowing in the muddy bottoms of local bays and protected back waters, in areas that are difficult to reach and almost impossible to walk on due to the plastic, very s