Why are the flippers of whales horizontal in comparison to tail fins of fish?
952619
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.
357195
Panaque fish have spoon-shaped teeth which they use to rasp at submerged wood. Bacteria in their guts convert plant cellulose into nutritious chemicals.
514779
it all has to do with pressure, the internal pressure of a fish matches the pressure of the surrounding sea, in other words, they are of equal pressures, more or less
836803
Interesting that you should ask....Jacques Cousteau had made some very interesting observations on the subject. He noted that dogfish do indeed wag their tails when happy. More interesting tho was the fact that catfish purr when pleased and sea horses jumped for joy. Star fish glow at the thought of a visit from you, and on occasion a clam will show his mussels with pride.\n\nIf there's one thing I know, Cousteau otter know his fishes.
4073
Cephalopod transtates literally to Head Foot.  THey are a class of mollusks that include squids and octopi.
890414
Salamanders have a 'sprawling' stance.  This means that the limbs are positioned so that they extend sideways from the body before they bend to touch the ground.  Mammals have an upright stance, where the limbs are positioned underneath the body.  This change allowed for easier locomotion in mammals - they can move more quickly and with a longer stride.  \n\nThis chapter ( http://www.chemek.cc.or.us/ncsr/menu%20of%20products/documents/mampg9.pdf ) has some good info about mammal skeletal anatomy, and how it has evolved.  This article ( http://homepage.mac.com/wis/Personal/lectures/limb-evolution/LimbEvolution.html ) has some info about limb evolution.  Hope that helps!
905959
Yes. Bilateral symmetry. The are symmetrical from side to side.\n\n;-D Don't go in the water when they are hungry!
1081049
Many organisms possess vestigial structures that have no apparent function, but that resemble structures their presumed ancestors had. Humans, for example, possess a complete set of muscles for wiggling their ears, just as a coyote does (table 22.1). \n\nBoa constrictors have hip bones and rudimentary hind legs. Manatees (a type of aquatic mammal often referred to as "sea cows") have fingernails on their fins (which evolved from legs). Figure 22.17 illustrates the skeleton of a baleen whale, which contains pelvic bones, as other mammal skeletons do, even though such bones serve no known function in the whale. The human vermiform appendix is apparently vestigial; it represents the degenerate terminal part of the cecum, the blind pouch or sac in which the large intestine begins. In other mammals such as mice, the cecum is the largest part of the large intestine and functions in storageusually of bulk cellulose in herbivores. Although some suggestions have been made, it is difficult to assign any current function to the vermiform appendix. In many respects, it is a dangerous organ: quite often it becomes infected, leading to an inflammation called appendicitis; without surgical removal, the appendix may burst, allowing the contents of the gut to come in contact with the lining of the body cavity, a potentially fatal event.\n    \nThe skeleton of a baleen whale, a representative of the group of mammals that contains the largest living species, contains pelvic bones. These bones resemble those of other mammals, but are only weakly developed in the whale and have no apparent function.\n    \nIt is difficult to understand vestigial structures such as these as anything other than evolutionary relicts, holdovers from the evolutionary past. They argue strongly for the common ancestry of the members of the groups that share them, regardless of how different they have subsequently become. \nComparisons of the anatomy of different living animals often reveal evidence of shared ancestry. In some instances, the same organ has evolved to carry out different functions, in others, an organ loses its function altogether. Sometimes, different organs evolve in similar ways when exposed to the same selective pressures.
763223
I guess to be "eel-like" having no legs, being aquatic and posses functional or vestigial or reduced fins. Lamprey move by moving their bodies back and forth, to create propulsin, this is undulatory. Sinusoidal movement is what snakes use, it is side to side "S" movements, where as eels and lamprey use more of an up and down movement, like a mountain chain (several mountains side by side) they say the undulating mountains.\n\nhope this helps!
390773
It's an example of a transition between lobe-finned fish and AMPHIBIAN vertebrates, not reptiles.  \n\n(Well, it is a reptile transition in the sense that it's part of the spectrum between fish and reptiles, but it's also part of the spectrum between fish and birds or fish and mammals, it just seems a bit forced to call it a fish/mammal transition to me.)\n\nMore importantly, it shows exactly the type of features scientists predicted it should have, confirming the most common theory about how vertebrates moved onto land.
589999
It is actually easier for fish to live in salt water than fresh water because the ionic balance of the water is closer to that of their own blood. Fresh water fish constantly have to pump out the excess water they accumulate due to osmosis. Marine mammals (seals, whales etc) maintain their ionic balance in water by having protective compounds in their skin which acts as a waterproof barrier.
350661
i think its because they feed on small fish that are visible from over the sea, or maybe they love what the humidity does to their hair/ feathers\naksugar06 what the hell are you talking about
48552
Fish are designed to swim. The obvious answer however is because they have fins and a strong tail that propels them through the water.
980672
Dolphins swim in front of boats. Not for play, but it is due to the Water around the bow of the boat creates a low pressure system. So, the dolphins get pushed by the boat and do not have to swim as hard to cover vast distance. \n\nAs for fish swimming under whales, it is the same reason. The huge whale disturbs the rigidity of the water making for easier swimming. That is of course if you are talking about fish right up against the whale. \n\nOtherwise, A fish following a whale is just following. Doubtful, it is looking for a scrap as many fish do not comsume kreel. As whales do.\n\nAnimals much like humans are Lazy when it comes to spending energy. Geese and ducks fly in Vee formations for the same reasons. Disturbance of the air.
613887
It's a baleen whale like the humpback and blue whale. It was called the Right Whale because it was the perfect whale for whalers to capture. It floated to the surface after being killed by harpooning and it had plenty of blubber that could be rendered for whale oil which was used to light lamps in the days before electric lights and other uses and its flesh was used as food.
862981
Seals evolved from some terrestrial animal because anatomical analysis shows a 5-digit fin.  It probably evolved from a bear or otter-like creature.   Many mammals spend the majority of their time in the ocean, and when feeding is more successful in the ocean than on land, aquatic adaptations derive.
837002
1. Studies show that during the development of the embryo, it takes different forms that "recap" the evolutionary process that has produced the animal which is about to be born. For instance, during human embryogenesis, foetus exhibit a tail, a feature that our distant ancestors have had.\n\n2. No, they do not share structural similarities. So they are not closelly related.\n\n3. It's convergent evolution: even though both organs have different origins (a fin is a bone projection, while the flipper is the equivalent of our arms), evolution tried to satisfy the same need : to move in water.