Creature of the week
Slipper limpet shells
Ribbed Slipper limpet Shell Maoricrypta costata – 35 mm
Smooth Slipper limpet Shell Maoricrypta monoxyla – 25 mm
Circular Slipper limpet Shell Sigapatella novaezelandiae – 25 mm
http://www.nmr-pics.nl/Calyptraeidae/album/index.html
Circular slipper shell
Left – The host shell as it lies in the
sand with a distinct smiley sign
beneath it indicating a slipper is
hiding there.
Right - the dead white cockle shell
has been tipped back to reveal the
small circular shell attached to its
undersurface feeding on plankton.
David Gray at Long Bay
Ribbed Slipper limpet Shell Maoricrypta costata – 35 mm
Smooth Slipper limpet Shell Maoricrypta monoxyla – 25 mm
Circular Slipper limpet Shell Sigapatella novaezelandiae – 25 mm
Circular Slipper limpet Shell Sigapatella tenuis – 10 mm (has a central apex and is the one
inside the dead shell at Long Bay in the above photograph)
Description:
All have a shelf inside which gives them the “slipper” appearance and name. This creates a
space where the gills can filter water, while below the shelf, the muscular foot can hold on to some object.
Ribbed – Larger, heavier, brownish and strongly ribbed, white- streaked with black inside.
Smooth – smaller and plain white with shape varying according to the surface contour of the place
where it has been living.
Circular – convex and circular with a small spiral curl. A horny external “skin” is washed off in the
dead shell.
Habitat:
All these shells are hitch-hikers, attaching themselves to various other shells where they can get
access to good flow of plankton bearing sea water. Often seen on the back of a catseye, or mussel, on the
underside of a dead beach shell (see photo above) and even inside the home-shell of a hermit crab.
Diet:
Filter feeder.
Reproduction:
All slipper shells change sex from male to female during growth. First the male becomes bisexual
and finally fully female. When small the males attach themselves to the large female near the opening where
they can reach the female genital aperture with their extensible penis. 12 – 24 yellow eggs are brooded under
the female until they are miniature shells.
References:
http://www.nmr-pics.nl/Calyptraeidae/album/index.html
Morton and Miller “ The N.Z.Sea Shore”
Margaret S. Morley “Sea Shells of NZ”
Cats eye
showing
smooth
slipper
limpet
latched on
and two
small
males
hanging
in close
bye!
Long Bay - David Gray