Natalie White
by on April 27, 2020
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What land animal has the largest eyes?

With a diameter of 5cm (2 inches), the Common Ostrich (Struthio camelus) is said to have the largest eyes of any land animal. They are about the size of a billiard ball and five times larger than the human eye! You can see when you look closely that their eyes are quite beautiful with long eyelashes to protect them. However, they take up so much room in their head that their brain is actually smaller than either one of its eyeballs. With such impressive eyes, ostriches can spot moving objects at great distance – something around the size of a large dog can be seen as far as 3km away during the day and about 50 meters at night.

The ostrich needs its large eyes to protect it from the variety of intimidating predators that it faces in life on the African savanna. Even though it has wings, the ostrich is a flightless bird, but makes up for this by running very fast. It can reach speeds of up to 45 miles per hour (72 kilometers per hour) and can frequently outrun many of its enemies. 

 

What sea creature has the largest eyes?

In the depths of the ocean, there are creatures to be found with even larger eyes. Researchers say that the colossal squid (Mesonychoteuthis hamiltoni) have the largest eyes ever studied in the animal world. They measure a whopping 27cm (11 inches) in diameter which  is roughly the size of a soccer ball and bigger than the average human head! This is also three times the diameter of any other animal including the largest fish eye – the swordfish which has eyes of 9cm in diameter. This would fit inside the squid’s pupil! Just as ostriches use their large eyes to locate predators, it is thought that the colossal squid need their enormous eyes to spot their main enemy the sperm whale and also to catch their prey. At these abyssal depths there is almost no daylight. The squid use their huge eyes to pick up light given off by jellyfish and crustaceans that flash when they are disturbed by larger mammals such as the sperm whale. This can be seen from 120 metres away which gives the squid enough time to get moving!

 

What mammal has the largest eyes, relative to body size?

Whilst we are on the subject of eyes, another animal worth mentioning is the tarsier, (family Tarsiidae), a small leaping primate found on various islands of Southeast Asia. One of their most noticeable features are their large Gollum-like eyes. It is believed that they have the largest eyes relative to body size of any animal. Each eyeball is around 1.6cm in diameter which is as large as the tarsier’s entire brain! Their eyes are so big that they are not able to rotate them so instead they use their neck, which can rotate a full 180 degrees in either direction, the same as an owls. Tarsiers are nocturnal and completely carnivorous so they need their large eyes to spot their prey, waiting silently for it to approach, instead of moving around to hunt.

 

What animal has the best vision?

Although these animals may have some of the largest eyes, it cannot be disputed that some of the best vision still belongs in the bird kingdom. Whilst all birds of prey have outstanding long-distance vision, eagles stand out as the best. They can see clearly for about eight times the distance that we humans can, which is essential for spotting their prey. However, as soon as the sun sets, owls take the top spot for night vision. Their large, tubular-shaped eyes contain more rods than human eyes, making them more light sensitive. Their eyes are also pretty huge for their size, accounting for up to 3% of their entire body weight. It seems that in the animal kingdom big eyes definitely seem to aid the quest to hunt down prey.   

 

 

 

 

Posted in: Birding, Educational