Differences between aquatic and terrestrial animals - simple explanation

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There are about 10 million species on the planet, which can be classified in various ways, depending on their type of diet, the mode of reproduction or the ecosystem in which they live, being able to distinguish, for example, between aquatic and terrestrial animals, which are two large groups. Do you know how to differentiate them beyond their habitat? Do you know the characteristics that allow them to live in one habitat or another?

In this Green Ecologist article we tell you in a simple way the main characteristics and differences between aquatic and terrestrial animals.

A common origin between aquatic and terrestrial animals

According to theories about origin of life and evolution, this started in the aquatic environment So there was a time, millions of years ago, when all of our ancestors were aquatic. Thanks to evolution, these were adapted until they also managed to conquer the terrestrial environment.

One of the most relevant adaptations was the development of the spinal column, which gave them greater mobility and, therefore, a greater chance of survival. It is followed by many other evolutionary changes, both structural and functional:

  • Limb development: giving rise to the first tetrapods. In addition to limb development, they also developed ribs, and some other bones and joints in order to be able to move better and cope with gravity.
  • Skin appearance: this allowed that the alive beings did not dehydrate, since the terrestrial dry air was not adapted for the fragile fabric of the aquatic species.
  • Respiratory system: they replaced the gills, which needed an aquatic environment to obtain oxygen with lungs, which allowed them to obtain oxygen in the terrestrial environment.
  • Reproductive system: little by little oviparous reproduction, through the laying of eggs, was replaced by viviparous reproduction in which the individual develops inside its mother.

The why of the adaptation to the terrestrial environment It is due to increased competition and struggle to survive in the aquatic ecosystem and the Devonian drought periods, which produced the imminent need to conquer and adapt to terrestrial habitat.

Basic differences between aquatic and terrestrial animals

In summary, these are the main differences between aquatic and terrestrial animals:

  • The habitat in which they live.
  • The breathing.
  • Feeding.
  • The reproduction.
  • Other physical characteristics for adaptation to the environment.

Next, we explain the characteristics that most differentiate these two types of animals.

Main characteristics of aquatic animals

The aquatic animals They are those who live either their whole life in water or, at least, most of it. They present some characteristics that allow them to survive in this element, to be able to develop and perform their vital functions:

  • Feeding: Phytoplankton is the main food of the aquatic food chain since zooplankton feed on it, and mollusks feed on zooplankton, continuing this chain until reaching some larger animals such as sharks or sea elephants. However, not all use the same system when it comes to obtaining or consuming their food, since the characteristics of their digestive systems can be very different.
  • Reproduction: they can reproduce sexually or asexually. In the case of sexual reproduction we can distinguish between those viviparous such as dolphins, whales or killer whales; oviparous, typical of most fish and ovoviviparous such as shark. As for asexual reproduction, as is the case with starfish.
  • Breathing: Most aquatic animals breathe through gills, capable of absorbing dissolved oxygen in the water, while others have lungs, so that, although they live in water, they need to raise or store oxygen from the surface to breathe, such as in the case of dolphins.
  • Physical characteristics for adaptation to the environment: Not only the organs for respiration have been adapted to the aquatic environment, but in these animals we can also observe fins for nothing, types of skins suitable to survive in said environment, adaptation of vision, and so on.

There are different types of aquatic habitats, depending on the characteristics of the water, temperature and type of currents, among others, being able to distinguish between saltwater animals, typical of seas and oceans, or freshwater animals, typical of rivers and lakes.

Main characteristics of land animals

The land animals they are those who live on earth. However, these animals are very different from each other, so it is difficult to establish a series of characteristics that define them,

  • Feeding: the diet of terrestrial animals is very varied, since as in the case of aquatic living beings we can distinguish between carnivores, which feed on other species, herbivores, which feed only on plant species and omnivores, which are they feed on other species, both plant and animal.
  • Reproduction: the vast majority of terrestrial organisms reproduce sexually, being able to find viviparous organisms such as bears, dogs and cats; oviparous, as for example in the case of chickens and ovoviviparous, as occurs with some terrestrial reptiles.
  • Breathing: Absolutely all land animals take the oxygen necessary to survive from the air through different mechanisms. The most common is through the lungs, although there are some species that breathe through tracheae or book lungs.
  • Physical characteristics for adaptation to the environment: As in aquatic animals, terrestrial animals have specific characteristics to adapt to their habitat. For example, they do not have fins to swim like aquatic ones, but rather legs, wings or after shapes that allow them to move on land and in the air. Mainly, they have hair, feathers or certain types of scales.

There are very different terrestrial habitats, with different climates, temperatures, topographies and endless differences, in the case of deserts, tundras, tropical forests, taigas, sheets, grasslands and jungles.

If you want to read more articles similar to Differences between aquatic and terrestrial animals, we recommend that you enter our category of Animal Curiosities.

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