Cheetahs are known for being fleet-footed, reaching top speeds of 65 to 75 miles per hour. But there’s one type of fish that can be aptly described as fleet-finned, giving cheetahs a run (forgive the pun) for their money. Sailfish — specifically the Indo-Pacific sailfish (Istiophorus platypterus) and Atlantic sailfish (Istiophorus albicans), the two primary species of sailfish — can zoom around at up to 68 miles per hour.

While sailfish typically swim at a speed between 20 and 35 miles per hour, they can achieve double that in short bursts, typically when chasing prey. This is despite the fish’s immense size, as the average adult sailfish measures 11 feet long and weighs 211 pounds. But their sleek bodies allow them to glide through water with ease, and their powerful crescent-shaped caudal fins (or tails, in layman’s terms) propel the fish forward with incredible strength at lightning-fast speed.

Galeophobia is a surprisingly common fear of sharks in swimming pools, though thankfully, the odds of finding a Great White in the pool are slim to none. However, if a shark were to make its way into a pool, it’d have no trouble tracking down anyone with a fresh wound. That’s because sharks boast an incredibly powerful sense of smell, and can detect a single drop of blood in an Olympic-sized swimming pool.

Olympic-sized pools hold 660,430 gallons of water, and a drop of blood would be imperceptible to the naked eye. But a shark’s nose is highly sensitive, and used solely for smelling rather than breathing. This allows some sharks to detect the smell of blood or prey at one part per 10 billion, and in many cases from hundreds of feet away — or the length of several football fields, to use another sports analogy.

Shrimp may be small, but they have one of the strangest body plans in the animal kingdom. Their heart, for example, sits so close to the brain that it’s effectively inside the head. A shrimp’s heart is located inside the cephalothorax — the fused body section that combines its head and thorax beneath a hard protective shell. Since a shrimp doesn’t have a distinct neck separating its head from the rest of its body, the heart ends up sitting just behind the brain, making it appear as though it’s tucked inside its head.

Unlike humans, shrimp have an open circulatory system. Instead of pumping blood through a network of arteries and veins, their heart pushes a copper-rich fluid called hemolymph into open spaces surrounding their organs. This fluid delivers oxygen and nutrients before eventually making its way back to the heart to begin the cycle again. It’s an efficient design for the small crustacean.

In addition to being exceptionally brainy, octopuses also have a lot going on in one of their other vital organs: the heart, or hearts, of which they have three. Two peripheral hearts pump blood to the gills, while the central heart pumps that oxygenated blood throughout the body. This unique arrangement also explains why the elusive creatures are known to prefer crawling along the seafloor rather than swimming: their third heart stops beating while they swim, which consumes more energy and tires them out faster than crawling. Work smart, not hard.

This isn’t the only oddity in octopuses. Octopus blood is blue, as it contains a copper-based oxygen carrier called hemocyanin that helps the cephalopods thrive at cold temperatures; human blood (and that of other vertebrates) is red because it contains hemoglobin, an iron-based oxygen carrier. Hemocyanin is a less efficient oxygen carrier than hemoglobin, leading some biologists to speculate that octopuses have three hearts to compensate for that deficiency.