Does a starfish have a brain or not?
481474
A starfish does not have a brain. I it has a central nerve cluster instead.
1065310
Sensory and nervous system\nFishes have well-developed nervous systems that organize around a central brain, that is divided into different parts. The most anterior, or front, end of the brain are the olfactory bulbs, which are involved in the fish's sense of smell. Unlike most vertebrates, the cerebrum of the fish primarily processes the sense of smell rather than being responsible for all voluntary actions. The optic lobes process information from the eyes. The cerebellum coordinates body movements while the medulla oblongata controls the functions of internal organs. Most fishes possess highly developed sense organs. Nearly all daylight fish have well-developed eyes that have color vision that is at least good as a human's. Many fish also have specialized cells known as chemoreceptors that are responsible for extraordinary senses of taste and smell. Although they have ears in their heads, many fish may not hear sounds very well. However, most fishes have sensitive receptors that form the lateral line system. The lateral line system allows for many fish to detect gentle currents and vibrations, as well as to sense the motion of other nearby fish and prey. Some fishes, such as catfish and sharks, have organs that detect low levels electric current. Other fishes, like the electric eel, can produce their own electricity.
422928
I would have to say porpoises/dolphins...\nAccording to this article, they are smarter than chimps and possibly as intelligent as man...\nhttp://www.amusingfacts.com/facts/Detail/smart-porpoise.html\n\nAlso see:\nhttp://en.wikipedia.org/wiki/Dolphin_brain\nhttp://www.daviddarling.info/encyclopedia/D/dolphins.html\nhttp://www.wdcs.org/dan/publishing.nsf/allnews/239F297BE9A133F380256FC700323B80\nhttp://whales7.tripod.com/policies/levasseur/levass2f.html
1010312
yes.\n\nthey are mammals and do not breathe underwater.\n\nthey take in air at the surface, so it does not matter what type of water they live in.
284835
Maybe a brittle star? Other than that... there are many different types of starfish some with four arms some with a bunch of arms.\n\nhttp://en.wikipedia.org/wiki/Brittle_star
429593
No it is not a fish because fish are vertebrates and jelly fish are invertebrates.
184692
Fishes have eyeballs, two of them in their optic capsules, just like all other vertebrates. They're surrounded partly by bone, and partly by an elastic but resistant capsule. \nBony fishes don't have eyelids, but sharks and rays do\n(see answer at \nhttp://answers.yahoo.com/question/index;_ylt=AqPoH8mhQReCU_CYDM1Fvirsy6IX?qid=1006030500996 )\n\nAnd they _do_ have nostrils, but, as you have rightly deducted, they're not used for breathing. \nIf you look at a bony fish (a goldfish or whatever you have at hand) you'll see that it has TWO nostrils on each side of its snout (they can be close together or really distant). Between these two nostrils of each side there is a tube with special olfactory (smelling) cells, like the ones we have in our own noses. The water with chemical "smell/flavor" molecules goes in through the anterior opening, and flows out through the posterior opening. Thus, fish nostrils (derived from the primitive pair of olfactory capsules) are used for smell/flavor perception, and not for breathing (which occurs at the gills). \nIt's only in tetrapods (from amphibians to reptiles, birds and mammals) that the connection between the nostrils and the respiratory system occurs (and the lungs appear). If you open a frog's mouth (please only try it with a dead animal!) you'll see two paired holes in the roof of its mouth. Those are the internal nostrils (called "choanae") and they allow passage of breathing air to the mouth--> pharynx--> lungs. \n\nAdditional trivia:\n- Our own internal nostrils open way back in our pharynx, because we have a secondary palate.\n- Cartilaginous fishes have only one nostril on each side of the snout. However, each nostril is partly separated into 2 parts by a flap of skin, and actually water flows through the nostril just as in bony fishes.\n- Some bony fishes, the cichlids (discus, Jack Dempsey), have only one nostril on each side of the snout.
349380
We don't know that humans are the only creatures that can think deeper.  There's evidence that whales are quite intelligent.  Not to mention there's an awful lot of universe out there to contimplate.
517409
Fishes have well-developed nervous systems that organize around a central brain, that is divided into different parts. The most anterior, or front, end of the brain are the olfactory bulbs, which are involved in the fish's sense of smell. Unlike most vertebrates, the cerebrum of the fish is primarily processes the sense of smell rather than being responsible for all voluntary actions. The optic lobes process information from the eyes. The cerebellum coordinates body movements while the medulla oblongata controls the functions of internal organs. Most fishes possess highly developed sense organs. Nearly all daylight fish have well-developed eyes that have color vision that is at least good as a human's. Many fish also have specialized cells known as chemoreceptors that are responsible for extraordinary senses of taste and smell. Although they have ears in their heads, many fish may not hear sounds very well. However, most fishes have sensitive receptors that form the lateral line system. The lateral line system allows for many fish to detect gentle currents and vibrations, as well as to sense the motion of other nearby fish and prey. Some fishes, such as catfish and sharks, have organs that detect low levels electric current. Other fishes, like the electric eel, can produce their own electricity.
537537
Regeneration ability varies betwen species, but in general yes. Starfish can regrow any point that is lost. They can also regrow entire arms and in many species they can produce two new individuals if a section of the central disk is removed along with the arm.\n\nAnd I think everyone is well aware that starfish are not fish. Just as they know that crayfish are not fish, and that ladybirds are not birds, and that prairie dogs are not dogs, and that trouser snakes are not snakes.\n\n\n"Sea stars", sheesh.
256741
Bony fishes don't have eyelids. Cartilaginous fishes (sharks and rays) have a more or less developed lower eyelid thay may or may not have a nictitating membrane (a transparent extra eyelid). In any case, sharks close their eyes for protection when they bite, not for sleeping. And the upper eyelid is just a tegumentary fold.\nSee a nice illustration here (from Elasmoworld):\nhttp://www.elasmoworld.org/biology/anatomy/shark/external/diagrams/eye.gif\n\nFish sleep with their eyes open (the definition of fish "sleep" is not completely agreed upon, some researchers speak of "sleep-like behavior").\n--------------------\nKamannchie_girl, what do whales have to do with the question? You'll only confuse people if you mix whales with fish.
1071274
You have fish in inverted commas, does that mean you are unsure?  Did it have eyes, a mouth, gills?  Was it a vertebrate? The first thing I thought of was a sea slug or flatworm.  A sea slug seems more likely in a Carribean coral reef.
888715
Externally they have spines, tube feet, pedicellaria, all of which are attached to the calcium carbonate test. The muscles attached to all these parts allow movement of these parts. At the ventral mouth reveals their "aristotle's lantern" aka their fancy mouth-mouthparts designed much like garbage disposal blades.  The 5 white teeth set up like a grinding-beak can eat away at the kelp bed.  Inside they have some organs, mostly reproductive organs that hold their gametes between spawnings-breedings.  They also have a digestive system with an anus. They have a water vascular system inside which circulates water for a hydraulic pump, NOT blood!
95547
This all comes down to the way that vertebrates evolved, and it is a classic example of evolution producing a workable though complicated design that no intelligent designer would ever produce unless she were on drugs.\n\nTo explain let’s go back to the very earliest chordates. We are going back here to a time before our ancestors were fish, before they even had backbones. These things existed as essentially free-swimming worms a few inches long. No fins, no jaws, not even a real mouth, no limbs of any sort, just a body and a head. Every body segment aside form the head was identical and had just 4 muscle blocks. \n\nThese things lived by swimming around in the water filtering plankton from the water through a hole in their front end. That hole wasn’t a mouth, it was just a hole lined with beating hairs that drew in water.\n\nWith such a simple body plan these creatures didn’t require much nervous control by the ‘brain’ to the body.  Each body segment was controlled by a simple reflex arc from those 4 muscle blocks to the spinal cord. The brain could make them more or less responsive to stimulation and so cause the animal to turn left or right, but direct control from the brain to the body was extremely limited and there were correspondingly few nerves running from the brain to the body.\n\nWhat I haven’t mentioned is that this creature had EYES, and therein lies the reason for the crossing over. The early chordate brain was excessively devoted to operating some rather complex eyes that allowed it to see both  food and predators. So why are the eyes so important? Because when light enters they eyes it… crosses over. It inverts. You can follow the link below to get a better idea of this, with diagrams. But for now simply remember that the eye has a lense, and a lense inverts an image left to right as well as up and down. So with a brain devoted to processing inverted images collected through a lense it makes sense for the left brain to control the right body.  After all the information that comes from the left eye will in large part be telling the brain about conditions on the right side of the body.\n\n And so that is exactly what happened. These earliest chordates had (and still have) a brain with massive visual centres and limited  control of the body itself but, and this is vital, the left visual centres are largely located in the right brain. To move towards food on the left side of the body for example the signal form the left eye is processed by the right brain, and the right brain then sends the appropriate signals to the left body. To move towards visually acquired stimuli the signal has to cross over from the side of the brain that processed the data to the OPPOSITE side of the body.\n\nAs chordates became larger and more complex one of the things they did was to grow paired fins. They ceased being wormlike and became fishlike. But paired limbs require far more fine and centralised control than can be provided by a reflex arc to the spinal cord. So the brain assumed control. \n\nThe same brain that had evolved a complex crossover so that visual data corresponded to the correct side of the body was now being asked to assume direct control of paired limbs. Of course evolution works with what it has, not with what is best. The brain had a complex crossover for controlling the muscles of the body, and it couldn’t re-wire that, so it simply built on it. Limb control also crossed over form the left to the right brain even though it was no longer under visual control.\n\nAnd as we became more and more complex we simply kept the same convoluted design. The reason the left brain control the right arm today is simply because hundreds of years ago information form the left eye was processed by the right brain, which was a very sensible solution at the time.
472921
No they are really smart these days. King Triton has learnt how to make artificial limbs for all the sea-creatures. I heard that Ariel, the little mermaid has just had breast implants
323218
Yes fish sleep.They cannot close their eyes because they do not have eye lids.some fishes sleep with their one half of the brain at a time so that the other half is active n helps the fish in escaping predators.Some fishes sleep at the bottom n few float while sleeping.Some have particular sites for sleeping as we have beds.
491831
Most worms don't realy have a brain. They have nerve ganglia in their heads but they are too simple to be considered brains. The only worms that have what could be considered real brains are the acorn worms.\n\nCan they feel? Well they can sense, which is to say they can move towards food and away form some danger. But cabbages can do that as well. They can't feel in the sense that humans and other mammals can feel. They are not self aware and they can't feel pain, anxiety, joy and so forth