Difference Between Freshwater and Marine Water Animals

Freshwater vs Marine Water Animals

Animals that live in aquatic ecosystems are divided into two types; freshwater animals and marine water animals, and though both are adapted to live in water, there is some difference between them. Freshwater and marine water animals, including both vertebrates and invertebrates, are greatly adapted to live in water. Unlike the land animals, these aquatic creatures have entirely different set of adaptations to survive in the aquatic ecosystems. Since, aquatic ecosystems make over 90% of the entire ecosystems on Earth, it contains an enormous amount of animals with an extraordinary species diversity. This article focuses on the difference between freshwater and marine water animals while discussing the important features of each.

What are Freshwater Animals?

Freshwater animals are the invertebrate and vertebrate species live in freshwater ecosystems such as lakes, ponds, rivers, etc. The animals including fish species, crustaceans, mollusks, worm species, etc. are the main freshwater animal groups. In addition, certain other semi-aquatic freshwater mammals like otter, beavers, platypus, etc. are also found in freshwater ecosystems. It is believed that 41% of all known fish species are found in freshwater. Unlike the marine animals, freshwater animals have very different osmoregulation pattern. The problem with freshwater animal is the loss of ions (salt loss) from their body fluids to surroundings by diffusion. This leads to osmotic imbalance in their bodies. To maintain osmosis balance and prevent salt loss, freshwater animals uptake water and some ions in food and excrete urine with large amount of water and very little amount of ions. Moreover, freshwater fish can take ions across the gills into their body fluids.

Difference Between Freshwater and Marine Water Animals

What are Marine Water Animals?

Animals that live in marine water ecosystems are called marine animals. Enormous number of marine animal species are found in the ocean and seas than in any other ecosystem on Earth. Among the various ecosystems found in Open Ocean and deep sea, coral reef ecosystems contain the greatest number of species diversity than anywhere else in the ocean. Marine invertebrates including crabs, worms, mollusks, corals, jellyfish, etc. are found abundantly in marine ecosystems. Bony fishes and cartilaginous fishes, turtles, dolphins and whales are the marine vertebrates found in marine ecosystems. Unlike the freshwater animals, surroundings of marine animals have very high amount of salts. Because of the high concentration of salts, osmoregulators living in marine waters face the biggest problem of dehydration (water loss).To avoid this problem, these creatures uptake large amount of sea water and expel salt in that water across their gills and skin. In addition, the marine fishes expel a large amount of calcium, magnesium and sulfate ions with very small amount of water through the urine.

Marine Water Animals

What is the difference between Freshwater and Marine Water Animals?

• Marine animals are the animals live in marine ecosystems including seas and oceans. Freshwater animals the animals live in freshwater ecosystems like lake, ponds, etc.

• Freshwater animals have the adaptation to prevent ion loss, whereas marine water animals are adapted to prevent water loss.

• Amount and the species variation of marine animals are very higher than those of freshwater animals.


Images Courtesy:

  1. Freshwater fish by Odyssey3543 (CC BY-SA 3.0)
  2. Marin water fish by Cliff (CC BY 2.0)