Walking Fish Polypterus Senegalus Offers Glimpse At Evolution

Scientists are studying Polypterus Senegalus, a fish that can move in land, to understand how ancient organisms managed to jump from swimming in the waters to walking into land.

Polypterus Senegalus is a fish from Africa that is able to breathe air, move in land (with their fins) and resembles prehistoric fishes that managed to evolve into tetrapods - amphibians, reptiles, birds, and mammals. The scientists studied the fish to learn how these fish move to learn the evolutionary processes that occurred 400 million years ago.

By raising the fish on land for nearly a year, they noted significant anatomical and behavioural changes. The fish walked more effectively and its biological behavior adapted to the process. The researchers hypothesized that the behavioural changes also reflect what may have occurred when fossil fish first walked with their fins on land.

375 Million Year Old Fossil Show Evolution Of Hind Legs Started As Enhanced Fish Fins

The discovery of new fossil samples of a 375 million year old fish show that the development of hind legs happened before vertebrates transitioned to land and not after. The fossils show that legs started off as enhanced fish fins.

The fossils were of the prehistoric fish, Tiktaalik roseae, which is known as a transitional species between fish and land animals. The discovery of a well-preserved pelvis and a partial pelvic fin of the fish suggest that the development of hind legs started in fishes and not in land dwelling animals.

The pelvis had features comaprable to early tetrapods. It had a ball and socket hip joint and a highly mobile femur. Crests on the hip for muscle attachment indicated strength and advanced fin function. And although no femur bone was found, pelvic fin material, including long fin rays, indicated the hind fin was at least as long and as complex as its forefin.

The Tiktaalik roseae has a broad flat head and sharp teeth. Looking like a cross between a fish and a crocodile, the lobe finned fish can grow up to nine feet in length. Aside from having gills, scales, and fins, the prehistoric fish also had features found in land animals such as a mobile neck, robust ribcage and primitive lungs.

Tiktaalik roseae also had shoulders, elbows and partial wrists in its large forefins to provide support when it hunted in shallow freshwater environments. The researchers believe that aside from using the fins to swim like a paddle, the fish can also use it to walk with them as well.

Aquarium Based Skin Disease Caused by Mycobacterium Marinum Bacteria is Under-diagnosed

Aquarium Granuloma, a skin disease that is commonly associated with aquariums is under-diagnosed according to a study presented at the Infectious Diseases Society of America's annual meeting in San Francisco.

Aquarium granuloma is caused by the Mycobacterium marinum bacteria. The bacteria is a a non-tuberculous mycobacterium found in non-chlorinated water. Infection starts when an open wound on the arm or hand is exposed to the bacteria. The disease causes skin lesions and takes from 11 to 56 days to incubate.

People most susceptible to Aquarium Granuloma are those who work with fish or own aquariums

According to the study, patients with the disease may not associate it with aquariums because of the prolonged incubation period. Also, people do not usually tend to think of aquariums being host to bacteria. This may lead to the patient not getting the appropriate treatment.

The Nopili Rock-Climbing Goby And How It Climbs and Feeds

Gobies (family Gobiidae) have the most members in its family of fish. There are about 2000 species of gobies.

Mudskippers are part of the family. These fish stand out as they can crawl on land using their fins as legs. Despite this, they still have to return to water from time to time to keep their gills and fins moist.

The Nopili rock-climbing goby is also another species of gobies that has a peculiar trait. These fish can climb up rocks (usually up waterfalls). And as researchers have recently studied, using their mouths.

The Nopoli can be found in the islands of Hawaii, these fish live in mountain streams. Although as young juveniles, they start off on saltwater (the eggs are washed off into the sea where they hatch). As they mature, they make their way into freshwater streams. They feed off algae on the surface of rocks and gravel. They are also known as Oopu Nopili and Stimpson's goby.