Mexican blind cave fish, new research

This video is called Astyanax mexicanus.


Blind Cave Fish Traded Eyesight for Energy

Sep 14, 2015 04:55 PM ET // by Danny Clemens

At first glance, the blind cave fish is an example of evolution seemingly moving backward.

Over time, a handful of Mexican tetra (Astyanax mexicanus) living at deep depths have gradually lost not only their eyesight, but also their eyes, while their surface-dwelling counterparts have maintained their vision. Dubbed the “blind cave fish”, the eyeless creature also lost much of its pigmentation, growing to sport a body of fleshy pink scales.

According to new research out of Sweden’s Lund University, however, the blind cave fish’s lost vision is actually a major step forward in adapting the fish to its new environment.

Researchers conclude that a highly developed visual system can suck up to 15% of an animal’s “total energy budget”. For a fish living at deep, dark depths with an irregular food supply, that expenditure simply isn’t worth it.

“This is a tremendously high cost! Over evolution, this morph lost both eyes and visual cortex, without a doubt because of the unsustainable energy cost of maintaining a sensory system that no longer had any significance”, study lead author Damian Moran explains in a news release.

Instead, the blind cave fish has come to rely upon a finely tuned sense of smell and a keen sensitivity to changes in water pressure.

Scientists revealed last year that the fish has also ditched its circadian rhythm as an energy-saving measure.

“These cave fish are living in an environment without light, without the circadian presence of food or predators, they’ve got nothing to get ready for, so it looks like they’ve just chopped away this increase in anticipation for the day,” Plant and Food Research New Zealand scientist Dr. Damian Moran explained when his research was published.

The reduction of traits over time is known as “regressive evolution”, according to a 2007 study from New York University.

Young sturgeon found again in North Sea

This video shows Atlantic sturgeons (Acipenser sturio) in the Trocadéro aquarium in Paris, France.

Translated from the ARK conservationists in the Netherlands:

Thursday, September 10th, 2015

Almost three months after having been released in the Rhine one of the marked sturgeons was captured by a shrimp trawler in the North Sea. The shrimpers have reported their catch to Sportvisserij Nederland, WWF and ARK Nature. The rare sturgeon after the catch was put back in the water alive.

Marked sturgeon

The European sea sturgeon (Acipenser sturio), 78 centimeters in size, was caught on Thursday September 3 about four o’clock off the coast of Goeree-Overflakkee, about 15 kilometers from the Haringvliet sluices. The sturgeon was equipped with a mark with contact data in case of being caught. After measuring, recording of data and taking a picture, the sturgeon was put overboard in good condition by the crew of the VLI-7 Eben Haëzer from Flushing.

Great blue heron catches fish, video

This video from the Cornell Lab of Ornithology in the USA says about itself:

Great Blue Heron Poised, Strikes, Catches Fish, August 4, 2015

Great Blue Heron snatches a fish on the Sapsucker Woods Pond Cam.

White-tailed eagle catches eel, video

In this video, a white-tailed eagle catches an eel, while gulls fly around it.

Michael Kopijn made this video from the Sylka hide in Lauwersmeer national park in the Netherlands.

Great cormorant under water, video

This video shows a great cormorant swimming under water in the Netherlands.

On the left, a northern pike is visible.

Nico van Lier made the video.

Fish and birds in, near the botanical garden

Jackdaw, 7 September 2015

This photo shows a jackdaw on the bank of a canal. We met it on our way on 7 September 2015 to the big AquaHortus aquarium and terrarium exhibition in the botanical garden. All photos of that day are macro lens photos.

The aquariums near the entrance of the exhibition contained tropical fish. In aquarium #1 were South American species: Nannostomus beckfordi; Hyphessobrycon columbianus; and Corydoras arcuatus.

This video is called Colombian Red & Blue Tetra (Hyphessobrycon colombianus).

In aquarium #2 were many cardinal tetras; and Hyphessobrycon bentosi.

Next, an aquarium with blue discus fish. According to an exhibition organiser, they cost 250-300 euros a fish.

Piranhas, 7 September 2015

In aquarium #6 lived piranhas.

Piranhas, on 7 September 2015

Their colour was more pale than usually. Still stress of being transported to the exhibition, which started only two days ago.

Paradise fish male, 7 September 2015

Next, an aquarium with paradise fish, both a male and a female.

One story higher in the botanical garden building were many small aquaria. In some of them were blue shrimps.

Killifish, 7 September 2015

In others, killifish. Many of them colourful, like these ones in aquarium #121. Unfortunately, no name tag on the aquarium.

We continued to a hothouse. Many tiger barbs in an aquarium.

In the next hothouse, an aquarium with two tropical seahorse species: Hippocampus erectus from the Americas, and Hippocampus barbouri from south-east Asia.

We left the hothouse, and had to get used to the colder autumn open air temperature. Not a problem for the animals in the aquariums outside. They were North Sea animals, including sea urchins and crabs.

A bit further, there were aquariums with wildlife species living in the canals of Leiden city. Including invasive American crayfish. And various freshwater fish species: eel (both juveniles and older ones). And carp (juveniles, as adult ones would need too big an aquarium).

Also Cottus perifretum.

Perch shared an aquarium with zebra mussels.

Next, an aquarium with three young northern pike.

Then, an aquarium shared by two species: the smallest Dutch fish at the exhibition, three-spined sticklebacks.

Ruffe, 7 September 2015

And somewhat bigger, but still small, fish: ruffe.

Ruffe, on 7 September 2015

Next, a rudd aquarium.

Finally, a bream aquarium.

As we walked back, pondskaters in the stream in the garden.

On the bank of the pond, a grey heron. Twice, it managed to catch a fish: a roach?

Stay tuned, as there will be more blog posts about the AquaHortus exhibition, especially amphibians, reptiles and plants!

Big aquarium, terrarium exhibition in Dutch botanical garden

This 24 August 2015 video is about preparations for the AquaHortus exhibition, in the botanical garden in Leiden, the Netherlands.

From 5-27 September 2015, there will be that big aquarium and terrarium exhibition, called AquaHortus.

The displays will be in several botanical garden hothouses and other buildings and in the open air.

The plans say there will be 68 terrariums. And 95 big aquariums. And about 200 small aquariums, mainly for killifish and shrimps.

Among the fish will be tropical sea fish, tropical fresh water fish, North Sea fish and fish of the species in the canals of Leiden city.

In the terrariums will be snakes, chameleons and other lizards, turtles and tortoises, salamanders, poison dart frogs and scorpions.

There have been earlier AquaHortus exhibitions here.

In the 1950s, this was one of the first places anywhere were one could see luminescent neon tetras in an aquarium.

This is a neon tetra video.