Giant Coral Colony in American Samoa by Holly BolickBernice Pauahi Bishop Museum
Have you ever heard of a colonial organism? Most people would join you if you said “no”, but you probably do know at least one. Coral colonies that live in shallow tropical oceans are the most popular and well-known of all colonial organisms. A coral colony is made up of a group of individual polyps, sometimes numbering in the hundreds to tens of thousands, that are all connected and working together as one unit.
NMSAS - Ta'u Valley Of Giants (2014-02-12) by Wendy Cover/NOAAOriginal Source: Wendy Cover/NOAA
When these large networks of interconnected individual coral polyps work together, the result can be spectacular. Recent surveys have revealed some massive stony coral communities that are larger than buses, taller than giraffes, and older than 500 years. It’s incredible to think that there are coral colonies alive today that began growing around the same time Europe was just beginning to accept that the planets revolved around the sun rather than the Earth.
"Coral Reef Twilight Zone" Mesophotic Coral Ecosystem by NOAA and Hawaii Undersea Research LaboratoryOriginal Source: NOAA and Hawaii Undersea Research Laboratory
Others can create communities (with more than 100% coral cover) that span more continuous area than several football fields put together. These ancient animal colonies are living archives of the sea and provide a window into the history of the environment.
Colonial animals, such as corals, are actually much more common than you would expect. There are thousands-- possibly tens of thousands of species of colonial animals in this world and they can be found in nearly every marine habitat. The common feature that all colonial animals share is that they are discrete but physically connected individuals working together as a unit or a superorganism.
Stony Coral Galaxea horrescens, Papua New Guinea by Holly BolickBernice Pauahi Bishop Museum
The individuals are genetically identical and are connected by tissue and, in some cases, a shared circulatory system, but each individual has a function and they all rely on the rest of the individuals in the colony to carry out their functions successfully.
Close Up Coral Polyps by Bishop Museum Invertebrate Zoology CollectionBernice Pauahi Bishop Museum
The individuals cannot thrive, or even survive, if they all do not work together for the benefit of the whole.
Shallow water corals tend to be the most well-known but they are just a tiny sliver of the strange world of colonial animals. There are alien-like creatures called pyrosomes which are a type of pelagic tunicate (surprisingly, these animals are our closest relatives in the invertebrate realm), and can grow into a giant floating tube up to several meters long, large enough for a person to swim into.
These communal animals are made up of individuals, multicellular organisms called zooids, which are all connected and contained in gelatinous structures called tunics that function as “floating hotels” for other pelagic animals in the sea like small fish, shrimp, and crabs that find shelter, transportation, and food inside. Another amazing feature of these superorganisms is that they are able to bioluminesce as a community and emit waves of light.
Red Bryozoan (Integripelta bilabiata) (2018-06-16) by Christian SchwarzOriginal Source: Christian Schwarz
Bryozoans are a poorly known but beautiful group of marine invertebrates containing over 5,000 species of colonial animals. Also known as lace or moss animals, bryozoans have specialized zooids each encased in an exoskeleton that can form intricate and beautiful colonies of different shapes and sizes.
Lacy Bryozoan with Anemone by Scott JohnsonBernice Pauahi Bishop Museum
Also known as lace or moss animals, bryozoans have specialized zooids each encased in an exoskeleton that can form intricate and beautiful colonies of different shapes and sizes.
Some encrusting species resemble apartment complexes with individual zooids living in adjoining “apartments”, while the branching and lace forms look more like trees and shrubs with zooids resembling the blossoming flowers. Individuals are quite small (less than 1mm) while the entire colony can grow to over a meter.
An octocoral called Dendronephthya sp. In Kamiali, Papua New Guinea by Holly BolickBernice Pauahi Bishop Museum
There are many advantages to being a colonial animal: they can achieve extremely large sizes and can live extremely long lives; through their shared connections, colonial organisms are more resilient to disease and predation; and they are able to adapt to changing conditions more resilient to disease and predation; and they are able to adapt to changing conditions more efficiently than solitary organisms.
Coral Polyps by FGBNMS/SchmahlOriginal Source: FGBNMS/Schmahl
We as a species could learn much from colonial organisms and superorganisms. By acknowledging our connectedness and interdependence and functioning as a single whole, we would be better able to maintain a habitable environment and ensure our future survival.