multicelulare

Multicelulare refers to organisms composed of more than a single cell that adhere to each other, communicate, and differentiate to form tissues and organs. In multicellular life, cells specialize for different tasks—nutrition, support, movement, reproduction—and work together as a coordinated unit. This complexity contrasts with unicellular organisms, which perform all life processes within a single cell, and with colonial forms where cells cohabit but retain independent life.

Most familiar multicellular groups are in the kingdoms Animalia (animals), Plantae (plants), and Fungi. Other examples include certain algae such as brown and red algae and some green algae, as well as certain slime molds that develop organized bodies. Core features of true multicellularity include cell adhesion mechanisms to hold cells together, intercellular signaling to coordinate development, and the division of labor among different cell types. Extracellular matrix provides structural support and mediates communication.

Multicellularity arose independently in several eukaryotic lineages over evolutionary time. The fossil record shows complex multicellular animals emerging in the late Precambrian, with land plants appearing later in the Paleozoic era. The transition typically required innovations for nutrient transport, pattern formation during development, and regulatory networks that control cell differentiation and growth.

Reproduction in multicellular organisms can be sexual or asexual, often involving a developmental program that starts from a single cell such as a zygote or spore. Multicellularity set the stage for diverse life strategies, ecological interactions, and the evolution of complex body plans.