#Can sharks swim backwards skin#

A blue whales tongue is so large that fifty people could stand on it. Electric Eels can reach up to 2 metres in length and larger specimens can generate 500 volts of electricity.

#Can sharks swim backwards skin#

It can be argued, however, that the best strategy is to maintain an equal number of males and females to prevent a slow down in the reproductive rate of the species in case of increased mortality in one of the two sexes as a result of disease, increased predation, or other factors. Using its web-like skin between its arms, an octopus can carry up to a dozen crabs back to its den. Females can be more aggressive or males can be particularly 'valuable' if involved in nest making or in the defense of territories. Because of the greater flexibility of their pectoral fins, many bony fish can swim, whereas sharks cannot. The relative 'value' of each sex, however, depends on their behavior. Having more males than females can be advantageous for the survival of the species in cases where males are more aggressive than females. If the number of females is higher than that of males, the species as a whole must utilize more food resources. There are some sharks that can do both ram ventilation and bucal plumbing like the sand tiger shark that when is swimming fast, ramming water over its gills and they cannot pump. It is more expensive, however, to be a female since eggs contain stored nutrients and in many fishes large numbers of eggs are produced to ensure the survival of the species. There are also sharks that have this mechanism like the angel sharks and nurse sharks which do not need to swim to breath this mechanism is called 'buccal pumping'. Having more females than males can be seen as advantageous since fewer males are needed to fertilize females: One male can fertilize several females.

It is not always easy to explain the biological significance of sex ratios as observed in nature, hence the value of this question as a discussion topic.