The ocean is home to highly specialized predators, including dolphins and sharks, both celebrated for their speed. Dolphins are air-breathing marine mammals, while sharks are cartilaginous fish, representing one of the oldest vertebrate groups. Comparing their athletic abilities requires looking beyond a simple top speed number. Their different biology dictates how they generate and apply propulsion in the water.
Comparing Top Speeds
The fastest sharks generally achieve higher burst speeds than the fastest dolphins. The Shortfin Mako shark is an apex predator capable of explosive bursts estimated to reach up to 46 miles per hour (74 km/h). This acceleration is necessary for hunting fast-moving pelagic fish in the open ocean.
Dolphins, conversely, are built for sustained, high-speed travel rather than short sprints. The fastest dolphin species, such as the Common Dolphin or Dall’s Porpoise, reach maximum sprint speeds around 34 to 37 miles per hour (55 to 60 km/h). Although this is slower than the Mako’s peak burst speed, dolphins can maintain high speeds for much longer distances due to their superior endurance.
Anatomy Driving the Difference
The fundamental difference in speed capacity stems from their evolutionary history and resulting anatomy.
Propulsion
Dolphins, as mammals, propel themselves by moving their horizontal tail flukes in a powerful up-and-down motion. This vertical stroke is highly effective for generating thrust. It also allows the animal to easily move vertically in the water column to reach the surface for air. Sharks, in contrast, use the side-to-side movement of their vertical caudal fin, which is the standard method of propulsion for fish.
Metabolism
The fastest sharks possess a physiological adaptation known as regional endothermy, or being partially warm-blooded. This allows the Mako shark to maintain its red swimming muscles at a temperature warmer than the surrounding water. This enhances muscle power and recovery for short, high-energy bursts. Dolphins are fully warm-blooded, which provides the sustained metabolic output necessary for their superior endurance.
Drag Reduction
Hydrodynamics also plays a role in speed, particularly regarding drag reduction. Shark skin is covered in tiny, tooth-like structures called dermal denticles, which reduce turbulence and friction. These denticles adjust their effect based on the shark’s speed, aiding both efficient cruising and explosive acceleration. Dolphin skin is smooth and elastic, relying on its slickness and a thick layer of blubber to minimize drag and maintain laminar flow.
Speed Utilization and Hunting Strategies
The way each animal uses its speed reflects its primary hunting strategy. The Shortfin Mako shark is an ambush predator that utilizes its superior burst speed for surprise attacks on fast, agile prey. This strategy often involves a rapid, vertical lunge from below to strike before the prey can react. This explosive effort is visible when Mako sharks breach, requiring immense underwater velocity.
Dolphins are highly social and cooperative hunters, relying on sustained speed and coordination. They frequently employ collective tactics, such as forming a tight circle around a school of fish to compress them into a dense “bait ball.” This technique uses the group’s collective speed and agility to manage the prey. Their continuous, efficient swimming enables them to maintain formation and herd prey over extended periods.