Littorina saxatilis
The Sexy Snail
Introduction:
Partners in Slime
Background
information:
Littorina saxatilis
Taxonomic Info
Life History
Habitat
Stresses for
L.saxatilis to overcome
Invasive?
Background
information:
Tectarius muricatus
The Study:
Nahant Project
Methods
Results
Discussion
Sub-study:
Bermuda Project
FTaxonomic
Information:
Kingdom:
Animalia
Phylum: Mollusca
Class: Gastropoda
Order: Neotaenioglossa
Family: Littorinidae
Genus: Littorina
Species: saxatilis
Littorina saxatilis, also known as the rough periwinkle. It has a rough, ribbed exterior, with characteristic deep ‘sutures between whorls.' The snails have a variety of color morphs from gray, yellow, to dark. It is also called the sexy snail by our professor Deb Robertson because of its whorls look like swollen hips. L.saxatilis grows to be less than 8mm in length. It is primarily found in the high intertidal. Organisms here are not bathed with water as regularly as the rest of the shore. Therefore living here is harder. Mostly this region of the intertidal is wetted by wave splash.
FLife
History: L. saxatilis
is an ovoviviparous snail; It broods its eggs which
hatch as live young.
The eggs protect the snails offspring and may provide them with a nutrient
rich home until they hatch. The female snails brood the larvae in its
oviduct (Moran, 1999).
The production of crawling, live young from eggs reduces
reproductive losses and permits new born snails to take advantage of the
favorable conditions they find themselves in
(Marine
Life Information Network for Great Britain and Ireland).
They are already in the region of the intertidal they prefer
to call home (Moran, 1999).
Figure B. From
Moran, 1999. Egg ‘capsule’ holding a
Littorina saxatilis larva.
(C = capsule, l = larva)
As the species is characterized by low motility and ovovivipartiy, it may have significant genetic differences between even adjacent populations. (Sokolov, 2002) It can also lead to inbreeding and genetic isolation of populations.
FHabitat: It is a key species in the high intertidal benthic communities with an extensive native range in the eastern and western Atlantic in the Rocky Coast of North American and extreme upper intertidal salt marshes in Great Britain.
Distribution of L.saxatilis in Great Britain
Image from
the Marine Life Information Network for Great Britain
and Ireland
In these habitats it is typically found in crevices of rocks and under stones.
FStresses for L.saxatilis to overcome: Desiccation during the low tides is particularly threatening to organisms that, like L.saxatilis, live in the high intertidal. In order to minimize the effects of desiccation most organisms move to crevices or moisture rich patches. Most snails close their operculum and hide out to limit the effects of heat and water loss. Other organisms have adapted ways to survive. L.saxatilis can survive 42 days out of water! This may be achieved by its “globose” shape that maximizes water retention in their shells (Bertness, 1999). As L.saxatilis is exposed to air for 70% to 95% of the time, it has reduced aerial and aquatic oxygen uptake rates above 25 degrees Celsius and up to 44 degrees Celsius (its thermal maximum) (McMahon & Russell-Hunter 1977).
Predators of L.saxatilis include Carcinus Maenas the green crab and star fish, species of the genus Asterias (Bertness, 1999).
FInvasive? Compared to those animals that release planktonic larvae into the ocean, which results in great dispersal, L. saxatilis has a demonstrated the ability for wide dispersal and even successful invasion of new locations. L. saxatilis is native to the Atlantic Ocean but was discovered in San Francisco Bay in 1992 (Carlton and Cohen, 1998). L. saxatilis likely invaded by its association with Ascophyllum nodosum an Atlantic algae that is often used as packing material for shipments of live animals Littorina saxatilis has recently established itself quite comfortably in San Francisco Bay. For more information about the attempt to eradicate L. saxatilis from the area visit the Smithsonian Environmental Research Center.
ON to Methods
All information found on this site is for educational purposes only. Unless otherwise specified, all images are property of Kathryn Brown. For permission to use contact: Kathryn Brown (site creator) or Clark University Worcester, MA © 2004
L.saxatilis
picture taken by Deb
Robertson
L.saxatilis
L.saxatilis
Photo from Cal. Acad.