Tag Archives: tadpole

What do frogs eat — and other froggy facts you never wanted to know

Frogs are by far the most widespread amphibians — they make up almost 90% of all the current amphibian species. Frogs generally spend their time around bodies of freshwater, in areas that remain wet even during the summer. So, naturally, this influences their eating patterns.

Adult individuals of almost all species are carnivorous, most often preying on invertebrates such as worms, snails, slugs, and arthropods. It’s sometimes said that frogs are “insectivores”, but that’s not technically true. They’re often generalist carnivores, eating pretty much anything they can swallow. Sometimes, they will hunt reptiles, amphibians, even small mammals. They sometimes even engage in cannibalism, while some species mostly feed on plants.

When it comes to what frogs eat, the answer is both simple and complicated.

Image credits: Ed van duijn.

What frogs eat — the tadpole edition

Frogs typically have five life stages. They start out as eggs and then become tadpoles, tadpoles with legs, young frogs, and adult frogs. During their tadpole stage, they’re extremely different from their adult stage. Tadpoles generally lack limbs and have a tail, they breathe through gills and live exclusively in water. The metamorphosis from tadpole to frog involves some major biological changes, including a change in diet.

The diet of tadpoles is also different from that of adults. Tadpoles are typically herbivorous and their preferred food is algae. They also scrape leaves from the pond, if available. If you want to feed tadpoles (though you shouldn’t start randomly feeding tadpoles in the wild), greens are probably your best options. Lettuce, broccoli, baby spinach all work great.

However, tadpoles aren’t exactly picky. Most species are carnivorous at the tadpole stage, but in a pinch, almost all tadpoles would eat insects, mosquito larvae, smaller tadpoles, or even carcasses. In fact, several species have been found to be cannibalistic at the tadpole stage, and tadpoles that develop legs early are more likely to be eaten, so late bloomers are more likely to survive.

It’s a tough life for a tadpole, and being picky with food is a luxury you can’t really afford.

A curious (and probably hungry) tadpole. Image in public domain.

Adult frogs and what they eat

Frogs don’t really roam much; they tend to stick close to the water that is so crucial to them. Although some species can travel for several kilometers, it’s common for frogs to stay within a few hundred meters (usually less than 500 meters) around their pond area. As a result, they have to eat things that they can reliably catch around their area.

This being said, frogs will often eat any living thing they can fit into their mouths. If it flies, walks, or crawls and it’s not too big, frogs will often have a go at it. Aside from the common prey (bugs, worms, snails, slugs), they will eat smaller mammals, reptiles, fish, or even small marsupials. The list isn’t limited to only these. Frogs are true generalist predators, and anything small enough to be eaten by a frog could be eaten by a frog. Moths, butterflies, crickets, even bees — all could be found on frogs’ menus.

Frogs hunt by using their specialized tongue and spit. Frog spit is one of the stickiest substances on the planet, and frogs’ tongues can extend out at a whopping 4 meters per second, and can be retracted in 0.07 seconds — five times faster than you can blink.

Generally, frogs like to hunt. They don’t really like carrion or leftovers from other animals (though on very rare occasions, they might also eat it). When they eat things like slugs or other mollusks, they generally swallow the shell whole. They don’t really pay much attention, and if they’re hungry and they can snag something, they’ll generally go for it.

Drawing of several species of frogs. Image credits: Wiki Commons.

 This being said, a few species also eat plant matter; for instance, the tree frog Xenohyla truncata is partly herbivorous, and its diet includes a large proportion of fruit. Several other species of frogs have been found to consume significant quantities of plants, and the diet of Euphlyctis hexadactylus consists of 80% leaves and flowers (though its juveniles are insectivores.

During the winter, frogs hibernate, slowing their metabolism and surviving until spring from the food they’ve consumed. Some species dig a burrow for themselves, others bury themselves in leaves, while some merely sink to the bottom of the pond, half-covered in mud. During hibernation, they obviously don’t eat anything. Fun fact: some frogs can indeed freeze and survive frozen for months, coming back to life when they thaw.

What does the common frog eat

There are over 5,000 species of frogs, making up around 88% of all amphibian species on Earth, and researchers are constantly finding new species as well. Here, we’ve tried to address the question of what frogs eat generally, but let’s take a moment to talk about the common frog.

The common frog (Rana temporaria), true to its name, can be found across most of Europe, including Scandinavia, Ireland, and the Balkans. It can also be found across vast swaths from Asia, up to Japan. By and large, it’s the most common frog species out there.

The common frog’s eating patterns are greatly influenced by the time of year, and like many other frogs, they also enter a type of hibernation. When they are active, they mostly eat invertebrates: snails, worms, wood lice, and spiders. They have a keen sense of smell and can detect worms or other prey of interest. They also eat larvae from other common frogs.

What about toads, what do toads eat?

Although the difference between toads and frogs seems significant, and you occasionally come across someone who’s quick to point that out, the use of the name toads and frogs has no taxonomic justification. It’s more of an esthetic consideration. ‘Frog’ usually refers to species that are either fully aquatic or semi-aquatic and have moise, smooth skins, while toads are terrestrial and have dry, warty skins (although there are exceptions).

The European Common Frog (Rana temporaria, left) & European Toad (Bufo bufo, right) hanging out in a London garden. Image credits: Thomas Brown.

As a result, because toads and frogs are so similar, they eat kind of the same thing. Toads mainly eat insects and other arthropods. They often enjoy eating things like worms and crickets. Sometimes, toads will also hunt prey like small mammals or even other amphibians.

Notably, frogs and toads are useful as they can keep the insect population under control. But they can also cause substantial damage, and several species of frogs and toads are invasive. A notable example dates from 1935 when cane toads from Puerto Rico were brought to Australia to control the sugarcane beetle population. The idea backfired spectacularly. Out of 102 toads that were introduced, their numbers grew to over 2 billion. They killed the beetles alright, but they killed a ton of native species as well and have become a major environmental problem.

At the end of the day, there’s a bunch of different frogs out there, with different eating patterns. Generally, frogs are indiscriminate predators, but some have more varied preferences. Undoubtedly, there’s still a lot left to learn about species of frogs, especially species from remote areas.

Frogs are also faced with a number of environmental threats; the common frog may be common, but other species are under a great deal of pressure. Out of the around 5,000 species of frogs we know, 737 species are endangered and 549 are critically endangered, and over 100 have probably gone extinct in recent times already (that we know of — the reality is quite possibly even worse). Among the biggest environmental threats, frogs are faced with are habitat destruction and other invasive species.

This YouTube time-lapse of cellular division in action will have you hitting replay again and again

We’ve often talked about cellular multiplication or division, but have you actually ever seen it in action? Well, through the magic of modern technology and the cinematic flair of YouTuber francischeefilms, you’re about to have a front-row seat to the show.

Their time-lapse video shows a Rana temporaria / common frog tadpole egg on its journey from a humble four cells to several million, all in just 20 seconds.

That’s much faster than in real life. According to francischeefilms, the video took “about 33 hours at 15-17C approximately” to make.

“The whole microscope sits on anti-vibration table. [I]t doesn’t matter too much what microscope people use to perform this,” francischeefilms further explains on their YouTube page.

“There are countless other variables involved in performing this tricky shot, such as: the ambient temperature during shooting; the time at which the eggs were collected; the handling skills of the operator; the type of water used; lenses; quality of camera etc.”

The YouTuber had to design and put together his own equipment to capture these incredible shots, as well as get the lighting and microscope set-up exactly right.

But all that hard work certainly paid off — seeing a life just starting out with such enthusiasm is nothing short of amazing. So the next time division comes into discussion, you’ll know exactly what it looks like.

 

tadpole disease

New diseases threatens world’s tadpole population

A new highly infectious diseases has been observed in tadpoles from three continents, threatening global populations. The disease, which was identified and described by British scientists, is a distant relative of an oyster disease.

tadpole disease

Image via Wikipedia

“Phylogenetic analyses revealed that this infectious agent was affiliated with the Perkinsea: a parasitic group within the alveolates exemplified by Perkinsus sp., a “marine” protist responsible for mass-mortality events in commercial shellfish populations,” the study writes.

It’s a bad time to be a frog. 42% of frog species are listed as being in decline, frog habitat is being destroyed throughout the globe, and now, there’s a new disease to deal with. The disease is caused by single celled microbes, and has been already observed on three different continents.

Professor Thomas Richards, from the University of Exeter and author of the study describing the diseases said:

“Global frog populations are suffering serious declines and infectious disease has been shown to be a significant factor. Our work has revealed a previously unidentified microbial group that infects tadpole livers in frog populations across the globe. We now need to figure out if this novel microbe – a distant relative of oyster parasites – causes significant disease and could be contributing to the frog population declines.”

To make things even more worrying, the pathogens seem to thrive in all climates ranging from temperate to tropical, and the tadpoles seem to not be able to develop immunity.

This study, and the general decline of amphibians adds more evidence to the already established theory of the sixth mass extinction; so far, in its geological time, the Earth has underwent five major extinction. Now, a new one is happening, and we are causing it. To make things even worse, we’re only now starting to understand it.

“The decline of amphibian populations, particularly frogs, is often cited as an example in support of the claim that Earth is undergoing its sixth mass extinction event. Amphibians seem to be particularly sensitive to emerging diseases (e.g., fungal and viral pathogens), yet the diversity and geographic distribution of infectious agents are only starting to be investigated.”

 

An eye growing on the tail of a tadpole.

Tadpoles can see through eyes implanted in their tails

An eye growing on the tail of a tadpole.

An eye growing on the tail of a tadpole.

Most animals have eyes in the vicinity of their brains, typically inside the head, since these are very sensible organs that require a very sophisticated neural link. Recently, biologists at Tufts University have shown that they could implant working eyes in other locations as well, after they granted blind tadpoles vision after they implanted eyes in their tails. The findings might offer further insight into artificial visions and regenerative medicine.

The scientists experimented with 134 tadpoles of the African clawed frog Xenopus laevis, a popular lab pet for researchers worldwide. These had their eyes surgically removed, after which the scientists painstakingly implanted eyes in their torsos and tails.

An experimental set-up was devised with quadrants of water illuminated by either red or blue LED light. The arena, half illuminated in red, half illuminated in blue, would regularly switch between colors via software. The trick lied in the fact that whenever tadpoles when enter the red district, they would receive a mild electrical shock. A motion-tracking camera kept tabs on where the tadpoles were at all times.

Remarkably, it was observed that six of the tadpoles always kept away from the red half of the arena, hinting that they could see with the eyes implanted in their tails. These eyes came from other genetically engineered tadpoles that were instructed to grow a red florescent protein. This allowed the researchers to see whether the eyes sent red nerves outward in the body. Half the 134 recipient tadpoles had no such nerves grow, while about a quarter had nerves projecting toward the gut and the other quarter had nerves extending toward their spine. All of the six tadpoles that showed signs of vision had nerves plugged into their spine, meaning their new eyes were now linked to their nervous system.

“One of the things that this study showed us is that connecting a sense organ as complex as the eye to the spinal cord is sufficient to confer vision,” Dr. Michael Levin said. “So you don’t have to plug in to the actual brain.”

Does this mean that the tadpoles can see just as well as they used to with their original eyes? In reply to this vexing questions, the scientists’ answer is straightforward – they don’t know. “We have no idea what a tadpole is experiencing. This is a philosophical question that is not immediately tractable,” the researchers write in their paper published in the Journal of Experimental Biology.

It’s well worth noting that applications for this kind of research aren’t limited to regenerative medicine only, augmented technology for instance would have a lot to benefit.

“You may want to increase your sensory capacity with sensors that normal people usually don’t have,” he said. “This opens the possibility for attaching all sorts of peripherals to your body.”

Robot designers could also learn a thing or two from the findings, in terms of adaptive flexibility.

“You can imagine that information that comes from any sensory structure – any part of the body – is tagged in some way that uses a unique identifier,” said Dr. Douglas Blackiston, a post-doctoral associate. “So, the source of that information is not nearly as important as what the brain is sensing.”