- "True" limpets are found in these two superfamilies. They
include several very similar shells, but all are
solid conical shells.
In the true limpets, featured here, both nutrient and waste streams
enter just under the shell, through two, separate grooves in the mantle.
This characteristic is common to many primitive gastropods, all of which
comprise the Patellogastropoda and Vetigastropoda clades. Their volcano-like
cousins are the keyhole limpets, which differ in having a slit or top
opening for the waste stream (see, for eample, Fissurellidae).
Limpets, generally, do not have eyes and seem to be guided mainly by chemoreception
based on mucus deposits. Most are shallow water molluscs, but those in
the Lepetidae family are a subtidal species. All true limpets
The more flattened conical shells of the Patellidae family are ideally
shaped to protect them against being crushed by waves that pound against
the exposed rocky surfaces they cling to. Their large flat foot acts
somewhat like a suction cup to attach them. None are stationary. They
move about while grazing on vegetation and detritus, some making prolonged
trips away from their home base while the tide is in. Of considerable
interest is that on returning at dawn, they move about to reorient their
body for a precise fit into the scar they had excavated into the rock
surface --even after the rock is picked up and moved or re-oriented.
Species in the former Acmaeidae family are generally smaller. They tend
to seek out tide pools and other quiet locations, and the smallest may
attach to fronds of vegetation. The Acmaeidae do not apply suction for
attachment; rather, they find imperfections in the surface to use for
attachement. Like the Patellidae, they are also mobile.
In the deep water limpets of the Lepetidae family, their radula is especially
well designed for boring into rock. Recurved teeth are hardened with
iron and silicon oxides at the tips.
Currently, Collisella, Tectura, Notoacmaea and most species
formerly of the genus, Acmaea, are reclassified to the genus, Lottia (Carlton,
2007) . In these cases, "Acmaea" and "Notoacmaea" are
synonyms for "Tectura".
The several current families listed below and in the photo gallery are
defined by significant differences in soft tissue anatomy (established
by scanning electron micrography), chromosome
number, and shell microstrucure (Beechey,
2008; Sasaki, 1998).
- Class: Gastropoda
- Clade: Patellogastropoda
- Superfamily: Patelloidea
Families & Major Genera
- Lottiidae (shallow water)
- Genus: Lottia [Collisella, Tectura, Acmaea, Notoacmaea]
- Patellidae (shallow water)
- Genus: Patella
- Nacellidae (shallow water)
- Genus: Cellana
- Genus: Nacella
- Lepetidae (deep water)
- Genus: Iothia
- Genus: Lepeta
- Genus: Neomphalus
- Genus: Propilidium
Tectura scutum (Rathke, 1833)
synonym, Acmaea scutum (Rathke, 1833)
Lottia insessa (Hinds, 1842)
synonym, Acmaea insessa (Hinds, 1842)
1.1 cm-2.0 cm
Patella granatina (Linnaeus, 1758)