Frogs legs have sprung a big surprise – contrary to textbook biology, they have primitive kneecaps. The kneecaps are made of dense, fibrous cartilage rather than bone, and appear to be much better suited to soaking up the strains of leaping and jumping than the bony human patella.
The patella, also known as the kneecap, is a flat, rounded triangular bone which articulates with the femur (thigh bone) and covers and protects the anterior articular surface of the knee joint. The patella is found in many tetrapods, such as mice, cats, birds and dogs, but not in whales, or most reptiles.
Bizarrely, many of the ostrich's closest relatives don't have kneecaps at all. In 2014 Regnault showed that emus and cassowaries, and likely the extinct moa, all seem to lack kneecaps.
The answer is... Elephants! Elephants are the only animal to have four forward-facing knees. All other four-legged animals have at least one pair of legs with knees that face backwards.
We found that, to produce maximal-distance jumping, the skeletal system of the frog must minimally include a gimbal joint at the hip (three rotational degrees of freedom), a universal Hooke's joint at the knee (two rotational degrees of freedom) and pin joints at the ankle, tarsometatarsal, metatarsophalangeal and ...
Frogs legs have sprung a big surprise – contrary to textbook biology, they have primitive kneecaps. The kneecaps are made of dense, fibrous cartilage rather than bone, and appear to be much better suited to soaking up the strains of leaping and jumping than the bony human patella.
Frogs also have neither ribs or diaphragms; body parts that help humans breathe.
INTRODUCTION: The most common fact to know is that spiders have 8 legs while insects have 6 and also, spiders have 48 knees- 6 knees on each leg. Spiders don't have antennae while insects do. Spiders are not insects, but arachnids.
These eyes are large to both allow as much light in as possible and also allow for a wide field of vision. Eyes aren't the only thing spiders have eight of. Spiders also have eight legs arranged in four pairs.
In the case of the elephant, in fact, it's impossible. Unlike most mammals, the bones in elephant legs are all pointed downwards, which means they don't have the "spring" required to push off the ground.
Kangaroos. Kangaroos are well known as large, hopping mammals from Australia that carry their offspring in pouches. What may not be so well known, though, is that kangaroos cannot walk backwards. Their hopping movement is called saltation.
Animals without backbones are called invertebrates. They range from well known animals such as jellyfish, corals, slugs, snails, mussels, octopuses, crabs, shrimps, spiders, butterflies and beetles to much less well known animals such as flatworms, tapeworms, siphunculids, sea-mats and ticks.
The kangaroo knee is, as in other species, a complex diarthrodial joint dependent on interacting osseous, cartilaginous and ligamentous components for its stability.
One of the very many ways that platypus (and echidna) skeletons differ from every other living mammal is that they have bent elbows and knees, with their legs held out sideways from their bodies much like a lizard.
Leg anatomy
In dogs, the ankle joint is referred to as the hock or tarsus, and the wrist joint is the carpus. Dogs also have two knees and two elbows. The bones above the carpus in dogs are the same as in human arms—the radius and ulna.
Babies are born with a piece of cartilage in their knee joint which forms during the embryonic stage of fetal development. So yes, babies do have kneecaps made of cartilage. These cartilaginous kneecaps will eventually harden into the bony kneecaps that we have as adults.
All other known millipedes Millipedes sport far fewer legs than their name implies, with many species having fewer than 100 legs. Until now, the record-holder was a species called Illacme plenipes, a deep-soil dweller known to have as many as 750 legs.
The mantis shrimp's visual system is unique in the animal kingdom. Mantis shrimps, scientifically known as stomatopods, have compound eyes, a bit like a bee or a fly, made up of 10,000 small photoreceptive units.
Although chitons look very simple, these mollusks have a very sophisticated shell. Its outer layer contains up to 1000 tiny eyes, each a bit smaller than the period at the end of this sentence.
Just like any other animal, spiders are not excluded from releasing waste. Their way of releasing their poop and urine is combined through one source - from their anus. Their poop often consists of insects and waste products since those are their primary food source.
While some spiders catch prey with webs, others -- such as jumping spiders -- hunt using sharp eyesight. Because they don't have eardrums, scientists have always assumed that arachnids were deaf to airborne vibrations. But biologists at Cornell University have now shown that spiders can detect sounds after all.
“Surprisingly, we found that they also possess an acute sense of hearing,” he said. “They can hear sounds at distances much farther away than previously thought, even though they lack ears with the eardrums typical of most animals with long-distance hearing.”
Stomach. The stomach performs four main functions: mechanical digestion by contracting to smash up food, chemical digestion by releasing acid to help chemically break up food, and then absorption and secretion. The stomach is sometimes surgically removed as a result of cancer or trauma.
Scientists have now completed a draft sequence of the frog Xenopus tropicalis and found that the amphibian's genome contains remarkable similarities to those of the mouse, the chicken and, yes, even the human genome.
Scientists found additional similarities between the frog genes and human genes. For instance, genes in frogs have very similar neighboring genes as humans about 90 percent of the time.