Gannets are large seabirds that are known for their spectacular dives into the ocean to catch fish. Their streamlined bodies and powerful wings make them excellent fliers and divers, but can they actually swim as well? In this article, we’ll take a close look at gannet anatomy and behavior to determine if these birds are able to propel themselves underwater.
Gannet Anatomy
Gannets have several adaptations that enable diving and underwater hunting, but also present some challenges for swimming. Here are some key features of gannet anatomy:
- Streamlined body shape reduces drag while diving.
- Long, narrow wings provide thrust for diving at high speeds.
- Webbed feet provide surface area for propulsion in water.
- Densely packed feathers resist water saturation.
- Nostrils close automatically when diving.
- Strong legs and feet for plunge diving.
- Light bone structure to minimize weight.
The streamlined shape, webbed feet, and waterproofing feathers help gannets move through the water when diving. However, the narrow wings that are so effective for aerodynamic plunging do not provide much lift or thrust underwater. The light bone structure also results in buoyancy that could make swimming more difficult.
Feet and Legs
A gannet’s feet and legs are its main tools for propulsion in the water. Gannets have large webbed feet with sharp claws for capturing slick fish. While the webs provide surface area for underwater paddling, the legs are set far back on the body, making them less efficient for swimming compared to other water birds like ducks. The strong legs and powerful feet are adapted for plunge diving, but are not specially adapted for paddling or swimming motions.
Wings
Gannets’ long, narrow wings allow them to dive into the water at speeds over 60 mph. However, these tapered wings do not provide much lift or forward thrust once the bird is underwater. While the wings can be used for steering and stabilizing, they are not designed for effectively pushing the bird through the water for active swimming. The rigid feather structure and streamlining that serve gannets so well in the air become limitations when trying to paddle underwater.
Gannet Diving Behavior
By observing how gannets use their bodies during hunting dives, we can better understand if swimming motions are part of their underwater behavior. Here are some key aspects of gannet diving:
- Plunge from great heights to reach deep depths.
- Wings tucked tightly against body while diving.
- Propelled forward by momentum during descent.
- Use feet and wings for steering toward prey.
- Grab prey with beak or feet.
- Passive ascent aided by buoyancy.
- Mainly use wings and feet for stabilizing, not propulsion.
Gannets dive at steep angles, reaching speeds of over 60 mph as they plunge downwards. This momentum propels them deep into the water in search of fish. Their streamlined shape and retracted wings reduce drag during descent. Once underwater, gannets steer toward prey using their wings and feet, but do not appear to make swimming motions. Their ascent is largely passive, aided by their natural buoyancy. Propulsion seems to be limited to the initial high-speed dive.
Hunting Strategies
Different hunting strategies demonstrate how gannets rely on gravity and momentum versus active swimming:
- Plunge diving: Dive from height, let momentum carry them downwards.
- Plunge diving from water surface: Flap wings to gain height for a diving re-entry.
- Low diving: Dive from just above the water in shallower dives.
- Paddle-feeding: Sit on water and paddle feet to move slowly, snap up fish.
When plunge diving from greater heights, gannets depend on gravity and streamlining to descend. Low dives and paddle-feeding require more effort from the feet for propulsion. But even during paddle-feeding, their body position on the surface suggests any underwater propulsion is limited.
Underwater Footage
Analysis of underwater video footage provides further evidence that gannets do not engage in active swimming motions while submerged. Their wings remain tightly folded against their bodies as they descend. Their feet may make occasional sculling motions for steering, but their webbed feet are not designed for efficient underwater paddling. Instead, they rely on momentum to cover distance underwater.
Do Gannets Swim?
So can gannets swim? After looking closely at their anatomy and hunting behavior, the answer appears to be no. Here are some key points:
- Streamlined for diving, but not adapted for efficient underwater propulsion.
- Narrow wings don’t provide thrust underwater.
- Light bones increase buoyancy and make staying submerged difficult.
- Webbed feet aid steering, not powerful swimming strokes.
- Dive momentum provides underwater movement, not paddling.
- Minimal evidence of swimming motions in hunting dives.
Gannets are superbly equipped for diving into water from great heights. But while they spend a lot of time in the ocean, their anatomy and behavior suggest they do not actively swim underwater. Instead, gannets propel themselves using gravity, streamlining, and strategic plunge diving. Their impressive fishing abilities rely on precision diving, not paddling or swimming. So while gannets rule the air over the seas, they appear to leave the underwater swimming to other aquatic experts.
Comparison to Other Water Birds
Contrasting gannets with other marine bird species supports the conclusion that gannets are divers, not swimmers. Here’s how gannets compare to other seabirds:
Penguins
- Short, stiff wings provide underwater propulsion.
- Feet set far back for powerful kicking stroke.
- Densely packed feathers trap air for buoyancy control.
- Wings used for “flying” through water.
Penguins are adapted for swimming with their paddle-like wings and feet. Gannets lack these adaptations and do not actively swim.
Cormorants
- Wings adapted for both flying and swimming.
- Feet with all 4 toes for paddling.
- Long tail for steering underwater.
- Low buoyancy allows staying submerged.
With webbed feet on all 4 toes and oiled feathers reducing buoyancy, cormorants can actively swim and stay underwater. Gannets lack these specializations.
Albatrosses
- Long, narrow wings for soaring flight.
- Swim only occasionally, not true swimmers.
- Use feet to paddle short distances.
- Minimal underwater propulsion abilities.
Like gannets, albatrosses are adapted for soaring flight, not swimming. Their anatomy and behavior also show limited underwater propulsion.
In comparison to these other seabirds, gannets lack the adaptations required for powerful swimming and underwater maneuverability. Their skills lie in utilizing momentum during diving, not in paddling or swimming underwater.
Conclusion
Based on their anatomy and hunting behavior, gannets do not demonstrate true swimming ability. While their webbed feet allow some maneuverability underwater, they lack adaptations for efficient propulsion. Instead, gannets use gravity and streamlining to plunge downwards, relying on momentum rather than paddling motions. In comparison to penguins, cormorants, and other swimming birds, it’s clear gannets are specialized for diving, not active swimming. So next time you see a gannet folded up in a steep dive, admire its aerial grace, but know that it avoids flapping its wings underwater. When it comes to swimming, gannets appear content to leave that to the real experts.