Ngozi Inayoona

Asubuhi ya nne, Chiara alikuwa amechelewa. Aliingia na kahawa mbili kutoka baa ya kona. "Hatufanya jaribio la rangi kwa Polly," alisema.

The fourth morning, Chiara was running late. She came in with two coffees from the corner bar. "We have not done the colour test for Polly," she said.

Aliweka sahani tatu kwenye sakafu ya tanki. Nyekundu angavu. Bluu angavu. Njano angavu. Chini ya moja yao, kulikuwa na dome ndogo iliyofunika kipande cha kamba. Leo, kamba ilikuwa chini ya sahani nyekundu.

She put three plates on the tank floor. Bright red. Bright blue. Bright yellow. Under one of them, a small dome covered a piece of shrimp. Today, the shrimp was under the red plate.

"Hapa kuna kitu cha ajabu," Chiara alisema. "Pweza ni vipofu wa rangi. Macho yao yana aina moja tu ya kipokezi cha mwanga. Kwa kila jaribio tulilowahi kufanya kwenye macho yao, hawawezi kutofautisha rangi."

"Here is the strange thing," Chiara said. "Octopuses are colour-blind. Their eyes have only one kind of photoreceptor. By every test we have ever done on their eyes, they cannot tell colours apart."

Polly alitikisa kichwa chake.

Polly tilted her head.

"Na bado," Chiara alisema. "Tazama."

"And yet," Chiara said. "Watch."

Pasta alijikunja. Mikono miwili ilinyooka kwenye sakafu ya tanki. Ilipita juu ya sahani ya bluu bila kusita. Ilipita juu ya sahani ya njano bila kusita. Ilisimama juu ya sahani nyekundu. Mkono mmoja uliinua dome. Pasta alichukua kamba.

Pasta uncurled. Two arms went out across the tank floor. They passed over the blue plate without slowing. They passed over the yellow plate without slowing. They paused over the red plate. One arm lifted the dome. Pasta took the shrimp.

"Yeye si kipofu wa rangi," Chiara alisema. "Lakini si macho yake yanayoiona."

"She is not blind to colour," Chiara said. "But it is not her eyes that see it."

Katika miaka kumi na tano iliyopita, wanabiolojia wamegundua kuwa ngozi ya pweza imejaa seli zinazohisi mwanga. Molekuli zile zile zinazopanga retina ya binadamu zinapanga uso wa mkono wa pweza. Ngozi inaweza kugundua mawimbi tofauti ya mwanga. Katika baadhi ya spishi, ngozi inaweza kugundua rangi maalum.

In the last fifteen years, biologists have discovered that octopus skin is full of light-sensing cells. The same molecules that line a human retina line the surface of an octopus arm. The skin can detect different wavelengths of light. In some species, the skin can detect specific colours.

Hii ni jibu moja kwa kitendawili cha zamani: jinsi gani mnyama asiyeona rangi anajificha kikamilifu katika mazingira yenye rangi nyingi? Pweza aliye kwenye matumbawe anafanana na matumbawe. Pweza aliye kwenye mchanga anafanana na mchanga. Macho yake hayawezi kuona rangi. Lakini ngozi yake inaweza. Ngozi inaona kile ngozi inahitaji kuiga.

This is one answer to an old puzzle: how does a colour-blind animal camouflage itself perfectly into colourful environments? An octopus on coral matches the coral. An octopus on sand matches the sand. Its eyes cannot see colour. But its skin can. The skin sees what the skin needs to copy.

Polly alitembea kando ya ukingo wa tanki polepole. Hakuwa amewahi kufikiria kuhusu macho yake mwenyewe hapo awali. Wazo kwamba mnyama anaweza kuona kwa sehemu za mwili wake nyingine zaidi ya macho lilikuwa la ajabu.

Polly walked along the rim of the tank slowly. She had never thought about her own eyes before. The idea that an animal could see with parts of itself other than its eyes was strange.

"Tumekuwa tukichapisha makala juu ya hili kwa muongo mmoja," Chiara alisema. "Watu wengi bado hawawezi kuamini. Ngozi ya mnyama inaona."

"We have published papers on this for a decade," Chiara said. "Most people still cannot believe it. The animal's skin sees."