Crepidula fornicata (slipper limpet)
Crepidula fornicata (slipper limpet) is a marine gastropod of the family Calyptraeidae, which is one of the lophotrochozoan groups and is constituted by more than 50 species. This invasive invertebrate species, native to the eastern coasts of the northern United States, has colonised European coasts and is now abundant there. This species is a filter-feeder and also consumes phytoplankton; individuals form stacks on sandy or rocky bottoms.
- Adults can be held in aquariums.
- The life cycle can be carried out in aquariums. The reproductive period can be carried out outside of the normal seasonal times in the laboratory and the quality of the first larval stages has been optimised through the cultivation of microalgae to feed the larvae.
- In the natural environment, the reproductive period covers two-thirds of the year, from February to October, and adults are easy to harvest due to their abundance in shallow waters.
- Whatever their stage of development, larval or adult, the limpets are very resistant; broodstock can be maintained and handled in aquariums by feeding them with microalgae. The larvae can also be raised in the laboratory, using the same diet as that for adults.
- After removing their capsule, eggs and embryos are transparent and are thus suitable for cell imaging techniques, in toto hybridisation, and immunohistochemistry and for the use of fluorescent markers.
- Functional gene analysis is possible, eggs can be micro-injected with synthetic RNA or morpholinos. Gene inactivation is performed via the TALEN technique and transgenic gastropods can be produced using the CRISPR-Cas9 method.
Scientific advantages of this model organism
Since the beginning of the 20th century, interest for this species has grown as a model organism for reproductive biology and as an invasive species. It is also a model organism for the study of the evolution of developmental mechanisms, particularly in molluscs and in lophotrochozoans.
- Calyptraeidae are unusual in that they are protandrous hermaphrodites. First male, the individuals become female after the juvenile stage. This species has another peculiarity: females possess a spermatheca in which the sperm of several males is stored (several months). Each spawning event (5000 to 10,000 eggs) is protected with the eggs being encapsulated and brooded in the female for 21 to 28 days. This mollusc has thus developed a very efficient reproductive strategy.
- The early development of Crepidula fornicata within the same capsule is rapid and synchronous, providing a high quantity of embryos all at the same stage. They reach the 25-cell stage in 20 h at 22-23°C. The cell lineages have been well described and characterised.
- After hatching, planktonic larvae, which have a pelagic life style, develop for roughly one month, reach the metamorphosis-competent stage and then undergo metamorphosis. This process has been studied extensively to understand the mechanisms and in particular to characterise the factors that induce metamorphosis.
- In the family Calyptraeidae, five developmental modes have been observed, making these gastropods ideal for comparative approaches.
Available genetic resources:
- The construction of embryo cell lines is in progress, as well as gain and loss of function tests, construction of EST libraries, etc.
- The development of microsatellite markers has facilitated genetic studies of their reproduction and population biology.