Ocenebra erinacea is a murderous gasteropod (kind of a sea snail) found on the coasts of the British Isles. It attacks and eats slow moving or sessile prey. Its favorites are barnacles, mussels and oysters.

These preys are shellfishes themselves. Their soft and tender bodies are protected by a calcified armor (their shell) that can be shut tight when danger lurks by. To eat them one has to get past their shells. All the predators of shellfishes have their favorite techniques:

• we humans force the shells apart when we eat mussels and oysters,
• sea gulls drop shellfishes from the air to break the shells,
• sea otters use a stone and break shells open,
• sea stars use their powerful arms to force bivalves to open up,
• and so on.....

Ocenebra is just a little snail. It cannot break shells or force mussels and oysters to open. So how does it do it? What is its trick?

1. He climbs on the top of its prey and hold tight.
2. He bore a hole through the shell of its prey.
3. He inserts its proboscis (a very very long snout with the mouth at the end) and eat the flesh

How does he make the hole?

 Well... Ocenebra has a chemical drill (a gland called the Accessory Boring Organ) at the basis of its foot. This chemical drill secretes chemicals that dissolve and soften a small portion of the prey shell. The radula (a rasp at the end of the proboscis) then grates the softened material. These steps are repeated several times. At the end a small round hole will be made in the prey shell and Ocenebra will begin to feed.

Part of Elaine's PhD was to investigate the structure of this Chemical Drill:

• What is the overall structure of this organ?
• What are the different populations of cells? Their shapes? Their functions?