Sharks and their teeth


This video says about itself:

13 March 2015

In this informative Shark Academy episode, Jonathan Bird explores the different kinds of teeth that sharks have and what they are used for.

From eNatureBlog in the USA:

How Many Teeth Are In A Shark‘s Mouth?

Posted on Tuesday, June 28, 2016 by eNature

Sharks have been in the news the past week, with a number of attacks on bathers in the waters worldwide. And the Discovery Channel’s annual Shark Week was this week as well.

Whenever sharks are in the news, we tend to get lots of questions about them, especially their teeth.. It seems folks are fascinated by shark’s teeth—something for which there is no shortage in a shark’s mouth!

A Never-ending Supply

Wouldn’t it be nice if our teeth replaced themselves whenever we needed a fresh set? No more drills. No more crowns. No more denture adhesives. That’s what happens to sharks.

In fact, some sharks replace their teeth every few weeks.

So the answer to the question how how many teeth does a shark have is pretty easy… as many as they need!

A Mouthful Of Teeth!

While the number of teeth in a shark’s mouth generally ranges about 20-30, depending on the species, many shark species continue to generate teeth throughout their lives. So the[y] never run out…

The teeth inside a shark’s mouth are arranged in rows, like seats in a theater. While the outermost teeth do the work of grabbing, cutting, or crushing prey—their function varies from species to species—the inner rows of teeth mature. Then, when the shark sheds the worn outer teeth, the next row takes their place.

It’s a process that continues throughout the shark’s life, with teeth being replaced more frequently the more actively the shark feeds.

Ever encounter a shark’s teeth up close? If so, you’re in a very small minority. Despite all the attention they have received in the news the past few weeks, shark attacks on humans are actually quite rare. They’re generally no more eager to meet us than we are to meet them

Even so, it never pays to tempt fate! So pay attention to warnings when you’re swimming in areas know to be frequented by sharks.

Got a shark story to share? Tell us in the comment section below.

Click here to learn more about sharks found around North America.

How porpoises swim, video


This video from Harderwijk in Gelderland province in the Netherlands says about itself:

How porpoises use their fins

28 June 2016

Harbour porpoises use their tail fluke to move forward in the water. By moving the tail up and down they are able to go forward. By using the pectoral fins they can change their direction. The dorsal fin is to stabilize the porpoise in the water. Harbour porpoise Sven is demonstrating how it works in this short footage. Sven is currently a patient in the rehab centre of SOS Dolfijn.

European eel life cycle video


This video from the Zoological Society of London in England says about itself:

The Amazing Life Cycle of the European Eel

1 July 2015

Find out about the incredible life cycle of the Critically Endangered European eel and their amazing migration.

ZSL has been working to conserve these iconic London inhabitants as part of our Tidal Thames Conservation Project for the past 10 years. Find out more about that work here.

Budgerigars and linguistics, new research


This video says about itself:

Budgies are grammar pedants too

20 June 2016

Just like us, these parrots use the grammatical structure of unfamiliar phrases to work out what they mean.

From New Scientist:

20 June 2016

Budgies use grammar to find meaning in unfamiliar phrases

By Colin Barras

Budgerigars are grammar pedants too. Just like us, these parrots use the grammatical structure of unfamiliar phrases to work out what they mean.

There is evidence that some birds pay attention to the order of sounds in a song, but this grammatical behaviour has not been well studied.

Michelle Spierings and Carel ten Cate at Leiden University in the Netherlands made new songs by piecing together three different snippets of recorded bird melodies. They played budgies and zebra finches certain patterns – such as AAB or ABA – and trained them to peck only when they heard AAB.

Order of play

The researchers then played new combinations to the birds. Because the zebra finches had learned not to peck for ABA, they also did not peck for CCA – apparently focusing on the fact the A snippet was in the final position in both cases.

But the budgies were different, focusing instead on the structure of the song. They pecked when they heard CCA, recognising that this is the same pattern as AAB. “They followed the structure and were not distracted by the positional changes,” says Spierings – the budgerigars are structural learners when it comes to grammar, like humans.

The results provide more evidence for convergent evolution of vocal learning in humans and birds, say the researchers. For instance, a study in 2014 found that dozens of genes involved in human vocal learning are active in a similar way in the brains of birds including both the zebra finch and the budgerigar.

New Triassic marine reptile species discovery


This 2012 video, in Italian, is about Lariosaurus valceresii and Lariosaurus balsami Triassic marine reptiles.

Translated from Dutch NOS TV:

Amateur paleontologist finds skull of prehistoric reptile

Today, 06:05

Never before the animal had been found in the Netherlands; Lariosaurus. Now a 4.5 centimeter skull of the flippered fish-eater has been found in a quarry in Winterswijk.

Amateur paleontologist Remco Bleeker was the lucky one who found the skull. Bleeker, in everyday life a concrete repairer, is pleased with the find. …

Bleeker brought the skull for examination to Germany, where it was found that it was a Lariosaurus.

Muschelkalk

In the quarry at Winterswijk Triassic limestone is extracted from rock layers from the Triassic geological period some 240 million years ago. In the quarry Bleeker also once found a peculiar fossil of a toothy marine animal. This fossil, which was seen by experts as a missing link was even named after him: the Palatodonta bleekeri.

The skull of the lariosaurus has been given the name of the hamlet where it was found. “The first is named after me. Now it was time to honor the quarry,” says Bleeker, who gave his find on loan to Museum TwentseWelle.

The name of the newly discovered species is Lariosaurus vosseveldensis; after Vosseveld hamlet.

See also here.

The scientific description of the new species is here.

Attenborough on Darwin and the Galapagos


This June 2016 video says about itself:

Charles Darwin‘s Galapagos Discovery – #Attenborough90BBC

Sir David retreads Charles Darwin’s footsteps to follow how he made the discovery of evolution on the Galapagos Islands.

Rare pink grasshopper photographed


Pink grasshopper in Hoofddorp, photo by Suzanne Wieringh

Translated from NOS TV in the Netherlands:

Rare pink grasshopper spotted in Hoofddorp

Today, 15:21

It’s unlikely that you will ever really see one, but it happened to Suzanne Wieringh in Hoofddorp: she spotted a pink grasshopper. The rare animal was in her garden.

Suzanne wanted to pick up her daughter’s shoe when she saw something that was pinkish. “At first I thought it was a rose petal, but then it started to jump,” she says to the regional broadcasting organisation of North Holland.

A professor of entomology at Wageningen University explains that the phenomenon is known among biologists as erythrism. This is a deviation which is similar to albinism, only erythrism causes a reddish color instead of white.

It is difficult to determine how many pink grasshoppers are born. These grasshoppers quickly fall prey to predators because of their poor camouflage.