Can manatees see underwater?

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Manatees are intriguing and marvelous aquatic mammals. They typically live in shallow rivers, bays and coastal areas, preferring water that’s not deeper than 10 feet (3 meters). But on any day, they swim slowly and clumsily through the water eating underwater vegetation, such as water hyacinth, hydrilla, eelgrass and water lettuce. Then they come to the surface every four or so minutes to breathe in air. However, because they tend to swim closer to the surface, this places them at a huge risk of collision with watercrafts, a fact that has necessitated the enactment of manatee protection policies including no-entry zones and restricted speed zones in various waterways to protect the animals.

So can manatees see underwater?

Manatees have a profound eyesight. When they are in clear water the animals can see a long way ahead of them. However, because manatees always reside in dimly lit habitats they are used to not relying often on clear vision for their daily life. Actually their vision only helps them make sense of the general shapes in the water and avoid colliding with things, and not more than that. Manatee eyeballs are positioned far back on the head and are about half as big as human eyeballs. This, coupled with the fact that their body length is about 2 meters (9.8 feet) and they weigh 362-544 kilograms (800-1,200 pounds), means their eyes are too tiny to meaningfully aid them.

In terms of structure, manatee eyeballs have rod and cone cells just like human eyes. The rod cells help the animals see in low light while the cone cells help them differentiate colors and contrast details. But even with such cells in their eyes, manatees are not able to discern much with their limited vision. The sea cows are only able to discern blue and green light pigments, but can’t recognize many other pigments. Manatee eyesight is categorized as poor, quite close to nearsightedness. And if they took human eye tests, they’d actually be classified as blind.

How do they manage it in the water with their poor eyesight?

The poor vision of manatees doesn’t hinder them from thriving in their aquatic habitats. While they do not discern much underwater, they actually do not require clear, keen vision to spot food and their poor eyesight is just enough for them to navigate the sometimes murky waters and locate tasty sea grass, algae and other aquatic plant life. Even more, their bodies are covered in whisker-like hairs, known as vibrissae, which are rooted in blood-filled follicles connected to about 50 nerves and trigger nerve impulses when pressure changes occur in surrounding motion, helping the animals to traverse their habitats.

When there is increased pressure caused by surrounding motion, these follicles trigger nerve impulses much like the way the fish’s lateral line converts mechanical energy from the movement of water into electrical energy via nerve impulses. So the vibrissae act as a sixth sense, enabling manatees to move easily in dimly lit environments. They are also very sensitive and can feel vibrations as low as a millionth of a meter. Apart from the body hairs (vibrissae), manatees communicate through ultrasound frequencies and have a kinesthetic sense for detecting low-frequency sounds, which helps them adjust to their environment. Manatees don’t have natural predators to keep an eye on and so do not face increased risk of being preyed upon due to their poor eyesight.

There are a lot more interesting facts about manatees that you’d probably like to know. That’s why Captain Mike’s offers well-planned manatee tours to enable tourists to locate, see and swim with manatees. At Captain Mike’s, you will work with skilled, knowledgeable captains and use stable, comfortable and safe boats to cruise through manatee hideouts, enjoy interacting with these awesome mammals and learn more about how they behave and thrive in their habitats. For more information on manatees, manatee tours and boat rentals in Crystal River, visit the “Captain Mike’s Swimming With The Manatees” site.

Swimming with the Manatees boasts the best water adventure in Crystal River, Florida with lots of things to do for you and your family. For more information, contact us online, or call us at (352) 571-1888.

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