Theory:

Some plants live in the mountain, some live in the plain even some plants are found in water. Similarly, animals found in mountain are different from animals found in deep ocean. There are different places for plants and animals to live.
Every living creature in the world needs a place to live its life and reproduce. Such places are called habitats.
There are two major types of habitats such as:
  1. Aquatic habitat
  2. Terrestrial habitat
Aquatic habitat
 
"Aqua" means "water".
Habitats filled with water are called aquatic habitats.
If the water is fresh water then it is called fresh water habitat. If the aquatic habitat has marine or salt water then it is called marine habitat.
 
Fresh water habitat
 
Plants that live in fresh water habitat develop some special adaptations. Since the plants need to float in the fresh water pond or lake, the stems and leaves of the aquatic plants have air chambers.

Fresh water plants include water hyacinth, lilly, lotus. Victoria Amazonia is a fresh water plant which has a floating leaf so brad that it can withstand a weight of 45 kilograms.
Example:
Fresh water habitats include rivers, lakes, pools and ponds.
Important!
In India, Ganges river is the longest river and largest fresh water ecosystem runs over 2500 km. Nile river is the longest river in the world runs over 6000km.
water-lilies-2388843_1920.jpg
Victoria Amazonia
  
Marine water habitat
 
Earth is covered by more than 70% with marine water. Oceans do have a variety of plants and animals. Marine plants include marine algae, sea grass, marsh grass and phytoplankton.
 
Important!
Giant Kelp is the largest sea weed grows up to 30 meters.

White-spotted_puffer.jpg
Marine ecosystem - a sea grass bed
Reference:
 
Image credit:
 
Marine ecosystem : Free image from Wikipedia; https://en.wikipedia.org/wiki/Seagrass#/media/File:White-spotted_puffer.jpg
Victoria Amazonia: Free Image by Graham Hobster from Pixabay ; https://pixabay.com/photos/water-lilies-giant-amazonia-2388843/