Culturing

Culturing aquatic animals

A little bit of background…

Huh? Does this mean breeding? Yes, exactly! But reproduction in the aquatic world is extremely diverse and the work done in public aquariums is more often described as culturing or propagating, depending on the animal. Most saltwater fishes and invertebrates reproduce by spawning, which means they release their eggs and sperm into the water at the same time. Sometimes it can be difficult to find the right conditions to get an animal to spawn but, more often than not, the challenge is raising their offspring.

Saltwater fishes

Raising saltwater fishes is an extremely challenging task. Most animals in the ocean—not just fish—start life as part of the plankton; they hatch as microscopic and clear larvae, and go wherever the currents take them. Larval fishes will be in this stage for different lengths depending on the species and the water temperature. (Warmer means shorter, colder means longer!)

In this tank, larval clownfish are swimming in water that is filled with tiny animals called rotifers and brine shrimp.

Clownfish are in this larval stage for a few weeks. Once they grow through this stage, they metamorphose (or "settle") into their adult form—but miniature!

This is student-aquarist-me holding up a clear container of newly settled clownfish that were being moved. They graduated from the larval tank to the "grow-out" tank!

While clownfish may only take a few weeks to settle, temperate or cold-water animals may take a few months! Bluebanded gobies, for example—see a little bit about Monterey Bay Aquarium's efforts to raise them here (Tumblr). The specialized "MoLaRS" system featured in that post, created by Roger Williams University and New England Aquarium, is increasingly being used in public aquariums to attempt to raise saltwater fish species. New England Aquarium and Vancouver Aquarium (website links to their arctic lab and general propagation) have historically led efforts to raise saltwater fishes while the Tennessee Aquarium Conservation Institute has made great strides in native freshwater propagation and release.

Some other groups

Freshwater fishes

Unlike their saltwater counterparts, freshwater fishes are typically more capable when they hatch (into fry), and species may provide some level of parental care. In general, this process in freshwater fishes is more well known than in saltwater species.

Corals

Corals release their eggs and sperm into the water just like fish do. However, corals can be propagated asexually by… breaking them apart! Being a colony of animals helps, because they don't rely on specific body structures that would be in different places. (Our brain and our heart do different things, and we only have one of each in different places! Picture a worm being able to be cut in half and surviving as two.)

Any piece of these colorful corals above could be broken off to start a new colony. In growing and propagating them this way, public aquariums rarely need to collect them from the ocean. (And most you could purchase are propagated this way anyway!)

The process of breaking coral colonies is called fragmentation and can even speed up the growth process, resulting in more colonies more quickly. This technique is used for restoring coral in its natural environment, for example, by the Coral Restoration Foundation. Here's more about some institutions' work with corals and coral reefs:

Cephalopods

Octopuses, cuttlefish, squid, and nautiluses together form a group of mollusks called the cephalopods ("head-foot" in Greek). Cuttlefish and squid are hot species to have right now, but they have very short life cycles, so it's impractical to exhibit them without culturing efforts behind-the-scenes. They don't have a larval stage, they come out of the egg ready to go; however, unlike the live foods needs of other animals (such as the microscopic rotifers for the clownfish), cuttlefish and squid need large live foods rather quickly.

Flamboyant cuttlefish eggs (Metasepia pfefferi) with embryos just beginning to become visible off the yolk in each egg's center.
Flamboyant cuttlefish few-week-old hatchlings being moved, by yours truly.

If you're interested in learning more about cephalopod culture, check out this story of Monterey Bay Aquarium's work with various species.

Jellyfish

Jellies have very interesting lifecycles. Most jellyfish that you'll see in an aquarium reproduce sexually to form polyps, which attach to surfaces and look like tiny anemones. Aquarists keep little tanks of polyps, which then reproduce asexually under the right conditions, popping off little jellyfish that grow to form a bell.

For more information on jellyfish in aquariums, check out these links:

Other animals

Here are some more links!

So… what's the point?

Well… we don't know much about the life cycle of many species, so each time is like a complicated, ridiculous, stressful experiment. But when it succeeds, it's incredible! Not only are we learning and sustaining animal collections for display, we're reducing or eliminating the need to collect wild animals.

Some facilities that aren't public aquariums probably do more culturing than public aquariums do. Two of the most well-known, Biota and ORA, have had many species breakthroughs that they supply to the aquarium hobby.

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