Kulit yang Melihat

Pagi keempat, Chiara terlambat. Dia datang dengan dua kopi dari warung di sudut jalan. "Kita belum melakukan tes warna untuk Polly," katanya.

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.

Dia meletakkan tiga piring di dasar akuarium. Merah terang. Biru terang. Kuning terang. Di bawah salah satu piring, sebuah kubah kecil menutupi sepotong udang. Hari ini, udangnya ada di bawah piring merah.

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.

"Ini yang aneh," kata Chiara. "Gurita itu buta warna. Mata mereka hanya memiliki satu jenis fotoreseptor. Dari semua tes yang pernah kita lakukan pada mata mereka, mereka tidak bisa membedakan warna."

"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 memiringkan kepalanya.

Polly tilted her head.

"Namun," kata Chiara. "Perhatikan."

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

Pasta mulai bergerak. Dua lengannya merentang di dasar akuarium. Mereka melewati piring biru tanpa berhenti. Mereka melewati piring kuning tanpa berhenti. Mereka berhenti di atas piring merah. Satu lengan mengangkat kubah. Pasta mengambil udang itu.

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.

"Dia tidak buta warna," kata Chiara. "Tapi bukan matanya yang melihatnya."

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

Dalam lima belas tahun terakhir, para ahli biologi menemukan bahwa kulit gurita penuh dengan sel-sel yang peka cahaya. Molekul yang sama yang melapisi retina manusia melapisi permukaan lengan gurita. Kulitnya bisa mendeteksi panjang gelombang cahaya yang berbeda. Pada beberapa spesies, kulitnya bisa mendeteksi warna tertentu.

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.

Ini adalah jawaban untuk teka-teki lama: bagaimana hewan buta warna bisa berkamuflase sempurna di lingkungan yang berwarna-warni? Gurita di terumbu karang menyatu dengan karang. Gurita di pasir menyatu dengan pasir. Matanya tidak bisa melihat warna. Tapi kulitnya bisa. Kulitnya melihat apa yang perlu ditiru.

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 berjalan perlahan di sepanjang tepi akuarium. Dia belum pernah memikirkan matanya sendiri sebelumnya. Ide bahwa hewan bisa melihat dengan bagian tubuh selain mata terasa aneh.

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.

"Kami sudah menerbitkan makalah tentang ini selama satu dekade," kata Chiara. "Kebanyakan orang masih tidak bisa mempercayainya. Kulit hewan itu melihat."

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