In the diverse animal kingdom, some species are born with their eyes closed or with vision that is not yet fully functional, a state often referred to as “born blind.” This temporary condition is a normal part of their early development. It signifies that their ocular structures are still maturing, and they will gradually acquire clear sight over time.
Animals That Are Born Blind
Many familiar mammals and birds enter the world with their eyes sealed shut, relying on other senses in their earliest days. Puppies, for instance, are born with their eyelids closed, typically opening them between 10 to 14 days old. Their vision is blurry at first, gradually improving to near-adult acuity around eight weeks of age. Similarly, kittens enter the world with closed eyes, often opening them between 2 to 16 days, with vision gradually sharpening over weeks. Full visual capability in kittens develops around 8 weeks.
Baby rabbits, or kits, are also born blind and deaf; their eyes usually open around 10 to 12 days after birth. Other species like mice, hamsters, and bear cubs are born both blind and deaf. Many songbirds also hatch in a blind state, being entirely dependent on their parents for care and feeding. This temporary blindness is common among young animals needing extensive parental nurturing as they continue their development outside the womb or egg.
Understanding Born Blindness
The phenomenon of being born blind is closely tied to an animal’s developmental strategy, categorized as either altricial or precocial. Altricial species are born in an undeveloped, helpless state, often lacking fur or feathers, and are unable to move independently. Their eyes and ears are typically closed, and they depend entirely on parental care for survival and growth. This developmental pattern is seen in domestic cats, dogs, rodents, and many bird species like hawks and owls.
In contrast, precocial species are born relatively mature and mobile, with open eyes and often covered in fur or down, capable of moving and sometimes finding food shortly after birth. Examples include ungulates like horses and deer, and ground-nesting birds such as ducks. Being born blind in altricial species allows for a shorter gestation period, which can benefit the mother by reducing the time she is vulnerable during pregnancy. Their closure also protects delicate optical structures from bright light and potential injury in the new environment.
Life Before Vision Develops
For animals born blind, the period before vision develops is managed through the heightened use of other senses. Newborn puppies and kittens rely heavily on their developed sense of smell to locate their mother for nursing and identify littermates. Their sense of touch is also crucial for navigating immediate surroundings, seeking warmth, and understanding physical boundaries. While initially deaf, their hearing develops rapidly, with puppies responding to sounds between 12 to 14 days and kittens around two weeks.
Parental care is paramount during this vulnerable phase. The mother provides constant warmth, nourishment, and protection, as the young cannot regulate their own body temperature or defend themselves. She also stimulates essential bodily functions like urination and defecation, vital for survival. As eyes begin to open, vision is initially blurry and sensitive to bright light, gradually improving over several weeks until full acuity is achieved, integrating sight with other established senses.