This postcard is published by Tushita.
The following is NOT printed on this card.
Sea urchins are spiny, globular echinoderms in the class
Echinoidea. About 950 species of sea urchin are distributed on the
seabeds of every ocean and inhabit every depth zone from the intertidal
seashore down to 5,000 meters. The spherical, hard shells of sea urchins
are round and covered in spines.
The most easily recognisable sea urchins are round, often brightly
coloured and covered in sharp-looking spines.
‘Most modern sea urchins are round - they’re the regular sea urchins,' explains our echinoderm curator, Hugh Carter.
Sea urchins are omnivores. Their main diet is algae, but they eat some animals too, such as sea cucumbers, mussels and sponges.
As sea urchins move about on their tube feet, they scrape algae into
their mouth. Their unique chewing organ is called the Aristotle’s
lantern and includes complex jaws and five self-sharpening teeth.
If something nutritious lands on a sea urchin’s body out of reach of
their Aristotle’s lantern, they’ll use their tube feet to pass the food
to the mouth. Since they scrape up food from the ocean floor, it makes
sense that a sea urchins’ mouth is on its underside. They excrete waste
from an anus at the top of their body.
On this postcard, the sea urchins are on a bed of shiny, blue stones, which we know nothing about.