A multicellular organism is an organism that consists of more than one cell, unlike unicellular organisms. All species of animals, land plants and most...

unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists...

contain microorganisms. The third domain, Eukaryota, includes all multicellular organisms as well as many unicellular protists and protozoans that are microbes...

organelles. A multicellular organism such as an animal, plant, fungus, or alga is composed of many cells, often specialised. A colonial organism such as a...

identify cells that share morphological or phenotypical features. A multicellular organism may contain cells of a number of widely differing and specialized...

around 1.7 Ga, multicellular organisms began to appear, with differentiated cells performing specialised functions. While early organisms reproduced asexually...

In a multicellular organism, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ...

one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid...

Differentiation happens multiple times during the development of a multicellular organism as it changes from a simple zygote to a complex system of tissues...

Extracellular space refers to the part of a multicellular organism outside the cells, usually taken to be outside the plasma membranes, and occupied by...

Prokaryotes are single-celled organisms such as bacteria, whereas eukaryotes can be either single-celled, such as amoebae, or multicellular, such as some algae...

multinucleate organism, while the cells of the latter live separately until food runs out, at which time the amoebae aggregate to form a multicellular migrating...

most other anisogamous organisms, a zygote is formed when an egg cell and sperm cell come together to create a new unique organism. The formation of a totipotent...

An immortalised cell line is a population of cells from a multicellular organism that would normally not proliferate indefinitely but, due to mutation...

extracellular fluid (ECF) denotes all body fluid outside the cells of any multicellular organism. Total body water in healthy adults is about 50–60% (range 45 to...

An embryo is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of...

that arise by asexual reproduction from either unicellular or multicellular organisms inherit the full set of genes of their single parent and thus the...

in all known organisms, being found in species as diverse as the unicellular bacterium Escherichia coli and huge multicellular organisms like elephants...

have allowed organisms to go from a single cell organism to one of many cells. Soon after the emergence of these first multicellular organisms, a remarkable...

may be a prerequisite for specialisation of cells, as an asexual multicellular organism might be at risk of being taken over by rogue cells that retain...

early biogenic graphite to microbial mat fossils to fossilised multicellular organisms. Existing patterns of biodiversity have been shaped by repeated...

group Protista is not used in current taxonomy.) Among the organisms that are not multicellular, the largest are the slime molds, such as Physarum polycephalum...

used as a model organism. It was the first multicellular organism to have its whole genome sequenced, and in 2019 it was the first organism to have its connectome...

microscopic organisms. Multicellularity in some form has evolved independently at least 25 times within the eukaryotes. Complex multicellular organisms, not...

Mosaicism or genetic mosaicism is a condition in which a multicellular organism possesses more than one genetic line as the result of genetic mutation...

to the expression of different sets of genes. All the cells in a multicellular organism derive from a single cell, differentiating into variant cell types...

years old. These nematodes were believed to be the oldest living multicellular organisms on Earth. In 2023, it was reported that nematodes of the previously...

together as a whole. Microbes live everywhere in and on every multicellular organism. Many organisms rely on their symbionts in order to develop properly, this...

life, since eukaryotes include all complex cells and almost all multicellular organisms. The process is widely agreed to have involved symbiogenesis, in...

feature for complex multicellularity. Complex multicellularity is different from "simple" multicellularity, such as colonies of organisms living together...