Militarized marine mammals. dolphins and sealions.

from schneier on security:

Dolphins and sealions:

A Navy seal - actually a sea lion - took less than a minute to find a fake mine under a pier near San Francisco's AT&T Park. A dolphin quickly located a terrorist lurking in the black water before another sea lion, using a device carried in its mouth, cuffed the pretend saboteur's ankle so authorities could reel him in.

Earlier posts on the topic.