I know that coral don't move and hydra do and that coral don't have tentacles but hydra do but I don't know how else they differ.
129213
Coral and hydra are both in the phylum Cnidaria, but hydra are in the class hydrozoa and most coral in anthozoa.  Hydrozoa have two body stages: medusa and polyp, whereas anthozoa only have one: polyp.  Coral often live in large colonies, whereas hydra do not.  Coral are mostly dependent on food from their symbiotic relationship with algae- not so with hydra (but they can form sybiotic relationships with some algae), therefore depend on growing in sunlight.  Coral can also grow much larger in size.
530041
The tails of fish and whales are different because they are the result of different evolutionary pathways, not because of direct functional factors. It is in fact an example of what happens when organisms with different structures, abilities and constraints are faced with the same functional requirement. \n\nFish have relatively simple vertebrae; in most cases, the vertebral centers look like biconcave cylinders that contact each other. This type of vertebrae allow the vertebral column to undulate laterally, and the tailfins of fish have evolved in a vertical arrangement, so that the lateral axial movement of the body moves the tail to provide thrust.\n\nIn contrast, the vertebrates that evolved adaptations for life on land, the tetrapods, don't have this type of vertebra any more. Our vertebral bodies are locked together by means of special apophyses (outgrowths). And although lizards and snakes undulate laterally, we mammals have lost that flexibility (as part of a different body structure that allows a different arrangement of lungs for respiration, etc). However, we can flex the spine up and down (or forward and backward, in humans) and many mammals that are fast runners use dorsoventral flexion/extension as part of their locomotion (if you've seen a film of a running cheetah, you know what I mean).\n\nNow, aquatic mammals use their limbs (more or less transformed into flippers) and tail to move in the water. They use the same powerful up-and-down body undulation as their ancestors used on land; in fact, this undulatory locomotion has been documented for a fossil ancestral whale,  Ambulocetus (see link).\n\nSo in this case, as in many others, we see more than one solution, and all are "optimal" (both are hydrodynamically efficient), but different because their evolutionary paths were just different, not better or worse.
629184
Every answer so far has been wrong. I really wish people wouldn't just guess at the answers to get points.\n\nThere is a species of saltwater amphibian , but just barely. The crab eating frog of south east Asia  commonly lives in mangrove estuaries. It can survive and even breed in brackish water without diffciulties. \n\nIt can and does occasionally venture into water with salt levels equivalent to  the open ocean, but prolonged exposure dehydrates it and must retreat to fresher water to rehydrate every few hours.\n\nCrocodiles and turtles aren't amphibians. They are freakin' reptiles. They've got scales for pity's sake.
108965
These are general differences between monkeys and apes: \n\n1. apes have no tails\n2. apes have larger bodies and relatively larger brains \n3. apes have mobile, rotary shoulder joint which allows them to swing and hang from their arms (monkeys are quadrupeds that jump and run along the tops of branches or on the ground)\n 4. apes have wider torso and shorter, stiffer lumbar region
151356
Probably a mutualism in which coral provides structure, support, and security, while the algae provide energy for the coral.
231172
Starfish live on the bottom, in shallow and deep water.\n\nGiant tube worms have been found at great depths on the bottom.  Also crabs.\n\nSome jellyfish also live very deep where there is no light.
428083
Diamonds placed in water appear to disappear (other than any flaws in them).  When they are removed from water, they are not wet.
431903
They are both from the same taxonomic order, 2 different families.  They are very closely related... The family Crocodyloidea consists of about a dozen or so crocodile species... The family Alligatoroidea consists of caiman (from South America, don't remember how many species... 4 or 5???) and the only 2 true Alligator species.  the American Alligator and the Chinese Alligator.  And yes, the two do co-exist.  Alligators are almost strictly freshwater animals, while crocodiles have salt glands that enable them to inhabit fresh, brackish, and salt water.\n\nAs far as how dangerous they are... Either one has the capacity to kill you, but some crocodile species get much larger, and alligators are usually considered pretty placid animals that just want to be left alone.\n\nHere's an AWESOME resource, I love it to death.\nhttp://www.crocodilian.com
213500
Crabs run or move sideways because that is the way their legs bend. Crabs do not have ball-and-socket joints; many crabs have joints in their legs moving in a restricted number of planes so that they can only move sideways. Many crabs like the "Shore Crab" need to scamper sideways to avoid the legs getting tangled up with each other. \n\nMuscles work in pairs. A muscle can only retract, or pull; to lengthen again it must relax and be pulled back by another 'antagonistic' muscle. The muscle blocks in crabs are attached to the inner surface of the exoskeleton, including the ten tubular legs, including the legs with claws, or chelae, as well as other appendages.\nAslo,For animals, their body lengths are normally larger than the widths. For locomotion, animals usually move along the long axis of their bodies. As crabs run sideways, they are moving along the long axis of their bodies.
264955
er, here we go (and this is straight off the top of my head)\n\nNo skeleton (endo or exo)means that they cannot self support. (neg)\nNo real means of self propulsion (neg)\nMostly translucent (pos) (from a prey point of view)\nSome have stingers (pos) for food capture and defense\n\nand thats all i've got. It's been too many years since school. sorry
449180
Cnidarians live mainly in marine environments. Examples of cnidarians are the jellyfish, sea anemones, and corals. They are different from sponges because sponges have assymmetry which means they have no definite shape. Cnidarians have radial symmetry.
133412
The only living chordates that do not have backbones are the "protochordates", that is, the members of phyla Urochordata or Tunicata (sea squirts) and Cephalochordata (lancelets). These chordates have the primitive support structure, a dorsal notochord. \nAdult Tunicates lack notochords, except for the planktoninc and tiny Appendiculaceans.  Tunicate larvae (known as "tadpole larvae") _do_ have a notochord that supports their tails. \nThere are many genera and species of Tunicata; so if you do a Google Image search for either "Tunicata", "Urochordata" "sea squirt" or "salp" you'll get many good photographs.\nOn the other hand, the lancelets are much less diverse. Almost all are included in genus Branchiostoma, so if you look for "Branchiostoma" or "lancelet" you'll get what you're searching.
358509
disagree  it's got to be a shark  and they don't have swim bladders
537528
I can think of a few:\n\nFungi are actually more closely related to animals. They get their food from living matter.\nHowever, they are different from animals because:\n\nThey absorb their food instead of ingesting it.\n\nThey have cell walls.\n\nThey are stationary, like plants.\n\nThey are different from plants because:\n\nThey are heterotrophs.\n\nThey lack roots.
368143
Some do, most don't. The Nurse shark is an example of a shark species that sleeps. It has it's nap in daytime. You can find them under rock overhangs or in small caves. I've crept up to 10 footers having a doze. They wake at night and hunt the reef.\n Most other species, however , have to move to survive, so sleep is not an option.
118556
I think the phylum name means "nettle" - it comes from the latin cnida\nthe central cavity is the spongocoel\nAnd i believe that ctenophora have colloblasts on the tenticles which burst when they come into contact with prey, releasing sticky fibres. Some just have mucus covered tenticles. Cnidaria on the other hand are your jellyfishes sometimes with masses of tenticles, and uses stinger cells.\n\nI hope this helps - i will admit marine biology is not my speciality, but I have done a bit.
111228
The Annelida have bilateral symmetry .The annelids also have a one-way digestive system . It has a segmented anterior with 8 hearts in each. It also has a body cavity. \n\nThe Mollusks are also bilateral like the annelids. They have a good nervous system. They also have a one-way digestive system. They have a coelom like the . The classes of mollusks are the bivalves, which have two valves, which the name suggests. It has 2 shells and 3 layers also. It has a mantle and it lives in the water. It has gills and abductor muscles. It has an excurrent and incurrent siphon, which no other phylum has. There are the gastropods, which live in land and ocean. It has one shell and one foot. There are also the cephalopods, which has tentacles a foot that can either be a sucker or hook.