If you’ve ever wondered how the eyes of flatfish like flounder and sole ended up on one side of the head, you should take a closer look at a newly published article by Dr Matt Friedman.
Dr Friedman, who recently took up a post at Oxford University, has been investigating this mysterious eye migration using 50-million-year-old fossilized Acanthomorph fishes from Italy and France, and has managed to show that the change was slow and gradual rather than abrupt. Over millions of years, the positions of the flatfish eyes have gradually changed, little by little.
Addressing the Society of Vertebrate Palaeontologists’ (SVP) annual meeting at the University of Bristol today, Dr Friedman said: ”Flatfishes and their profoundly asymmetrical skulls have been enlisted in many arguments against gradual evolutionary change, precisely because it is difficult to imagine how intermediate forms might have been adaptive. My work provides clear evidence of the kinds of intermediates deemed ‘impossible’ by earlier workers and answers this long-standing riddle in vertebrate evolution.”
The most ancient Acanthomorph fishes had asymmetrical skulls, but the eyes were still located on both sides of the head. From these foregoers, intermediate species evolved and one of the eyes gradually moved across the head until both eyes ended up on the same side – millions of years later.
The flatfish group puzzled 19th century scientists trying to grasp the new Darwinian ideas, because during that epoch, the group’s fossil record was incomplete and it was unclear how the gradual migration of one eye could have come about. Today, a much broader range of fossil fish is available to science and Dr Friedman’s study included over 1,200 fossil specimens belonging to over 600 different species.
Divers enjoying the waters off Darwin, the northernmost island in the Galapagos, suddenly realised the presence of an amazing 33 feet (10 meter) albino whale shark (Rhincodon typus), and as if one sighting of an albino giant wasn’t enough, a snow-white southern right whale (Eubalaena australis) calf has now been spotted off the coast of Western Australia.
Common whale shark in the georgia aquarium. See picture of albino here
The whale shark encountered in Galapagos is and adult female and was first observed by naturalist Antonio Moreano as he guided a group of scuba diving tourists. “I told everyone to keep a distance and not disturb it so we all jumped in the water and followed it for five minutes.” says Moreano who also managed to get a few pictures of the awe-inspiring creature.
The young albino southern right whale lives in the whale nursery waters off Western Australia together with its 60-tonne mother. It has been given the name Wilgi Manung, which means “white whale” in one of the indigenous Australian languages. According to Doug Coughran, a senior wildlife officer with the department of environment and conservation, Wilgi Manung might not be a pure albino since its eyes and nose does not display the characteristic pink flesh normally seen in albino whales.
Albinism is a hypopigmentary congenital disordered. It can be partial or total, i.e. characterized by a partial or total lack of melanin pigment. Albinism is caused by recessive alleles and must therefore be inherited from both parents to manifest. Albinism has been observed in many different animals, including mammals, birds, fish, reptiles and amphibians. The name albinism is derived from albus, the Latin word for “white”.