Koža koja vidi

Četvrtog jutra, Chiara je kasnila. Ušla je s dvije kave iz kafića na uglu. "Nismo napravili test boja za Polly," rekla je.

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.

Stavila je tri tanjura na dno akvarija. Jarko crveni. Jarko plavi. Jarko žuti. Ispod jednog od njih, mala kupola pokrivala je komadić škampi. Danas su škampi bili ispod crvenog tanjura.

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.

"Evo što je čudno," rekla je Chiara. "Hobotnice su daltonisti. Njihove oči imaju samo jednu vrstu fotoreceptora. Prema svim testovima koje smo ikad napravili na njihovim očima, ne mogu razlikovati boje."

"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 je nagnula glavu.

Polly tilted her head.

"Ipak," rekla je Chiara. "Gledaj."

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

Pasta se odmotala. Dvije ruke pružile su se preko dna akvarija. Prošle su preko plavog tanjura bez usporavanja. Prošle su preko žutog tanjura bez usporavanja. Zastale su iznad crvenog tanjura. Jedna ruka podigla je kupolu. Pasta je uzela škampe.

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.

"Nije slijepa na boje," rekla je Chiara. "Ali nisu njezine oči te koje ih vide."

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

U posljednjih petnaest godina, biolozi su otkrili da je koža hobotnice puna stanica koje osjete svjetlost. Iste molekule koje oblažu ljudsku mrežnicu oblažu površinu hobotničine ruke. Koža može detektirati različite valne duljine svjetlosti. Kod nekih vrsta, koža može detektirati specifične boje.

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.

Ovo je jedan odgovor na staru zagonetku: kako se daltonistička životinja savršeno kamuflira u šarenim okruženjima? Hobotnica na koralju odgovara koralju. Hobotnica na pijesku odgovara pijesku. Njene oči ne mogu vidjeti boju. Ali njena koža može. Koža vidi što koža treba kopirati.

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 je polako hodala uz rub akvarija. Nikad prije nije razmišljala o vlastitim očima. Ideja da životinja može vidjeti dijelovima svog tijela osim očima bila je čudna.

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.

"Već desetljeće objavljujemo radove o tome," rekla je Chiara. "Većina ljudi još uvijek ne može vjerovati. Koža životinje vidi."

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