which animal has the smallest brain?
217515
Its definately an OSTRICH! they are the only animals or birds that have a brain smaller than their eyes!
351561
Animalia\n\nThis is the scientific term for the animal kingdom (hence the hint, "But who is the king?")
67744
Yes they're tiny and they jump around. search google images for lice and flea pictures
543121
I would say Tardigrades also.  The smallest adult measured was 0.1 mm (100 micrometers).   When they are fully grown they can decrease their size a great extent when water is sparse making them much smaller than 0.1 mm, although this is a special case.
465891
Worms don't really have much in the way of a brain or nervous system, so I doubt they mind.  As far as other animals, I used to be against it but I've become rather desensitized to it... Many more animals are killed to become food or fur, or killed for sport... I have to deal with killing mice on a regular basis to feed snakes... They are low on the food chain for a reason.  A few humanely euthanized rats here and there for students to learn is a small price to pay.  As a bio student, there really is no replacement for learning first hand on the real thing.  My favorite dissection was a fetal pig in high school... Very interesting.  The only time I took offense was a mink dissection, and that is because the school was actually getting the minks from fur farms and paying for them, so our experiments were fueling the fur trade...
150984
largest is the femur, smallest is the stirrup of the inner ear.
161377
Amoeba are among the largest single celled organisms, far larger than any bacteria.  Some amoeba are large enough to be seen without needing a microscope!\n\nBacteria are the smallest living things and mycoplasms are the smallest living bacteria (known as nanobacteria).\n\nIf by creatures you mean animals, then the smallest depends a bit on your definition of "small".  The shortest is probably little Trichoplax adhaerens, which looks a bit like a hairy, multi-cellular amoeba.\n\nThe smallest animal in terms of number of cells is probably some kind of Mesozoa, a set of worms famous for being very short and only a few cells across, so much thinner than Tricoplax and less massive.\n\nThe smallest vertebrate is a species of fish that was just discovered recently, though I forget the name of it, sorry.  :-)\n\nIt's recently been discovered that a few single-celled organisms are, in fact, evolved from animals.  If you would count these as animals, they would be the smallest animals, though that would be merely a technicality.\n\nAll of this applies only to adult forms, of course.  We're all very very small to begin with!
666913
Gerbils???  wait, that's 7 letters long...\ngerbil...but you're really sick if that's what you mean...
5747
The smallest cell is a type of bacteria known as mycoplasma. Its diameter is 0.0001 mm. The smallest cell in the human body is the sperm cell.
634761
There are a few basic body types among mustelids: ferrets, weasels, minks, fishers, otters and martens all have that cylindrical long sinuous body and do the fast inchworm-hop run; badgers, wolverines, and skunks have broad flat heads and bodies and trundle or waddle along.\nSo if it runs like a ferret but is all-over dark, it may be a stoat or a polecat--depends on where you live and the size of the animal. See link as well.
12385
b) has the smallest mass
95921
10.  The kakapo- "It is notable for being the world's only flightless parrot, the heaviest parrot, and the only parrot to have a lek breeding system."\n9.  The hyena- "Hyenas are also highly intelligent predators, even more intelligent than the lions (some scientists claim they are of equal intelligence to certain apes)."\n8.  The Japanese Macaque- "They survive winter temperatures below -15 °C, and are perhaps most famous for the amount of time they spend relaxing in naturally heated volcanic hot springs."\n7.  The Galapagos Penguin- "It is the only penguin to live on the equator. "\n6.  The Horned Lizard- "At least four species also have the ability to squirt an aimed stream of blood from the corners of the eyes for a distance of up to 3 feet. This not only confuses would-be predators, the blood is mixed with a noxious biochemical that is foul-tasting to wolves, coyotes, bobcats, and domestic dogs and cats."\n5.  Naked Mole Rat- "Clusters of 20 to 300 animals live together in complex systems of burrows in arid East African deserts. They have a complex social structure in which only one female (the queen) and one to three males reproduces."\n4. Blue Footed Booby- "The courtship of the Booby consists of the male flaunting his blue feet to impress the female."\n3.  Mimic Octopus- "This octopus is able to copy the physical likeness and movement of different species like sea snakes, flounder, lionfish, and flatfish. It accomplishes this by contorting its body and tentacles and changing color."\n2.  Platypus- "The Platypus is considered to be one of the strangest specimens of the animal kingdom: a venomous, egg-laying, duck-billed mammal."\n1.  African Lungfish- "The African mudfish, or lungfish, can live out of water for many months in its burrow of hardened mud beneath a dried-up streambed."
131322
animal cells don't have a cell wall
51970
most likely fish, or another animal that lives in water, perhaps an early reptile
649299
Seeing-eye dog.\nWalks on four legs, like a chair (b/c a chair has 4 legs)
454691
animal cells are smaller and more numrous
329432
Jellyfish don’t have brains, and they aren't the only creatures that lack them. Sponges and a few other odd groups of animals also lack anything like a brain.\n\nJellyfish don't have brains because they don’t have any front or back. They represent a very early evolutionary experiment. At that stage animals had no front or back, instead the developed along the lines of a ball or disc. That body plan is very simple to construct, but balls and discs don't have any front or back.\n\nOther animals evolved brains because they have one part of the body that ALWAYS contacted food first as the animal moved around. That was the front end. And because there was one end that always came into contact with food first that end evolved the highest concentration of sense organs, and the highest concentration of nerves. That high concentration of nerves in turn evolved into a brain. Because they have no front or back jellyfish also never had the potential to develop a brain in the front end. \n\nI guess the question you need to ask is, if a jellyfish did have a brain where would it be? Since any part of a jellyfish has equal chance of can coming into contact with food there is no obvious place for a brain to evolve. Instead jellyfish have nerves scattered more or less evenly across the body, so all body parts are equally able to respond to stimuli.\n\nSo no, animals don't need brain to function. A brain is just a concentration of nerves. It is only useful if you can concentrate those nerves where most of the sensory input is going to arrive. For humans our eyes, ears, nose and tongue are all located in the head, providing a massive amount of sensory input, so it makes sense to have the processing nerves for those organs in the head too. The sense organs of jellyfish are scattered all across the body so it makes sense to have the nerves scattered too, and that is exactly what we see.\n\nNot having a brain hasn't prevented jellyfish and their relatives from being successful, and they have filled a great many ecological niches and evolved every major sense including hearing, smell, balance and even eyes.