Question

Can animals be unicellular?

Answer 1

Unicellular organisms are the organisms having a single cell. The reproduction occurs mostly by asexual means where only a single parent is involved that produces a similar offspring. These organisms do not depend on others for their survival and are able to perform their functions well.

Complete answer:
The unicellular organisms are the single-celled organism which includes bacteria, protozoa, algae, and unicellular fungi. The most commonly known unicellular species are amoebae and diatoms. Through the single-cell and with the simplest mechanism these organisms are able to survive throughout their life. They are the independent completely developed unicellular organisms that do not depend upon others for their basic requirements and perform all the functions and life processes to survive.
These organisms are found in various habitats that include extreme cold or extreme harsh and hot habitats. Their mode of reproduction is by asexual means that consist of binary fission, budding, regeneration, fragmentation, etc. They consist of both prokaryotes as well eukaryotes thus certain animals may also come under unicellular organisms. They have a special projection present on them which helps them in movement. By the process of diffusion, these organisms are able to take food and waste products in and out of their body respectively. The genetic material is also found inside them. They also constitute cell organelles that help them in performing various metabolic functions of their body. The types of respiration depend upon their type of habitat that may be either aerobic or anaerobic while the special respiratory organs are found to be absent in them.

Note:
The unicellular organisms that may include certain animals have simple body structure without any special or complex organs or systems that perform various life processes for their survival. They are thought to be existing long back since 3.8 to 4 billion years ago, thus are said to be the oldest forms of living organisms.