Nurse shark

Despite being a bottom-dwelling species, nurse sharks sit at the top of the food chain in Saba’s oceans, eating a diet of fish, crustaceans, and mollusks. They hunt primarily at night, hovering over the sea floor and using suction to vacuum smaller prey into their mouths, and the suction they create is so strong that it can pull a conch completely out of its shell! These powerful eating habits make them pretty unpopular within Saba’s hardworking fishing community, whose members have to contend with losing lobsters to hungry nurse sharks that pull them straight out of the trap. 

Young nurse sharks — which are often spotted, in contrast to adults’ uniform, light-brown coloration — prefer shallower waters, securing themselves in small crags in Saba’s reefs for safety. Mature sharks can also be seen sheltered in tight, rocky crevices, but become more likely to venture out into deeper reefs to prey on larger fish. During the day, nurse sharks can be seen resting in large groups on the seafloor, sometimes piled up on top of each other. Though not an aggressive species, they’ve been known to snap at humans who take advantage of their docile nature, so it’s still important to give them a bit of distance and respect when diving.

As sharks that often stay close to the seafloor, most of their diet lives there, too. Nurse sharks’ mouths are on the underside of their head, with a sensory barbel on each side to detect delicate movements in the sand, and their rows of sharp teeth point toward the back of their throat to keep prey animals from escaping once captured. On sandy seafloors, they can use their pectoral (front) fins to “walk” along the bottom of the ocean, and juveniles have even been seen to rest on the rear end of their pectoral fins with their head lifted above the ground — a behavior thought to create a tiny “shelter” for small fish and crustaceans to hide in … conveniently located right under the nurse sharks’ mouth.

Header image by @zahnerphoto (CC-BY-NC).