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Behavior and Breeding

The behavior of the Leafy seadragon is fascinating to watch and can be at times surprising. Normally thought of as slow moving animals, drifting in and out of the seaweed, Leafy seadragons are amazingly active. They spend most of their time moving between the blades of artificial kelp in the exhibit, and will occasionally “ride” the current in the aquarium, or “roll” upside down.

As feeding time approaches, the seadragons spend a large part of their time searching the bottom of the exhibit and in between the rocks for food. When cleaning the aquarium glass, or scrubbing the rocks, they often come near the scrub brush or pole and look curiously at it, most likely in the hopes that stirring up the gravel, or scrubbing the algae will uncover a previously undiscovered mysid shrimp. It can potentially be a dangerous curiosity, when cleaning the rocks or kelp could result in a slow moving dragon being trapped under a fallen rock.

Seadragons rarely display aggressive behavior, but in situations where there is a large number, or large-sized individuals in a small space, or where food availability is limited, Leafy seadragons have been observed “shoving” each other around in an effort to remove another individual from the area. This behavior can easily be confused with “dancing” which is described below.

Like other Syngnathids, the male seadragon is responsible for brooding the eggs. Unlike seahorses however, the male Leafy seadragon lacks a brood “pouch”, and the eggs are deposited in honeycomb-like indentions under his tail. These indentions develop at some point during the mating season, and will disappear at non-breeding times, making it very difficult to distinguish a male from a female Leafy seadragon. A female seadragon can deposit up to 250 eggs under her mates’ tail. The male will fertilize them and hold them for a period of up to eight weeks, at which time they will hatch over a period of a week (Kuiter 1988).

One of the most important issues facing public aquariums worldwide is the lack of information regarding the breeding behavior of seadragons. There has been no documented successful reproduction of seadragons in an aquarium environment. Previously, the inability of public institutions to maintain the animals long term has been certainly a contributing factor. Also, due to the difficulty and cost of obtaining the animals, institutions have not obtained large numbers of animals. They have also not experimented a great deal with these animals as they would with other less expensive and readily obtained fish. Another factor that may contribute to the lack of knowledge is that many institutions, with recently obtained animals, have juvenile specimens.

The gender of a seadragon can be difficult to identify, even in adults, but can be near impossible to distinguish in juveniles, making pairing difficult. In adult specimens, it is believed that the female has a deeper abdomen and thinner tail than males (Forsgren 2004). “Scute-like” structures on a female’s tail generally appear more pronounced than the male’s more rounded appearance. This difference is especially noticeable during breeding season when the male’s tail begins to swell to receive eggs. The Seattle Aquarium has been working on a research project that involves collecting fecal samples from juvenile Leafy seadragons and measuring the different hormone levels of these samples for differences based upon sex. It is undetermined whether this method will be a useful way of pairing dragons in the future (Whitney-Robinson 2003).

The behavior classified as “dancing” describes the side-by-side courtship display that is characterized by the dragons swimming in close contact and often in a circular pattern back and forth. This dancing also includes a frequently noted rise to the surface as a pair. Observations of dancing are common among public aquariums displaying dragons, with many of these institutions recording attempted egg transfer.

There have been only a few reports of successful transfer of eggs from female to male Leafy seadragons, and in each of these cases, the eggs have been dropped by the male soon after the transfer without any noticeable development of embryos. In contrast, the Weedy seadragon, Phyllopteryx taeniolatus, has successfully reproduced on a number of occasions in public aquariums such as The Aquarium of the Pacific, Long Beach, California and the Tennessee Aquarium, Chattanooga, Tennessee (Forsgren 2004).

It is believed that Leafy seadragons may require a deeper column of water in order to successfully transfer the eggs. In addition, lighting and temperature may also play significant roles.

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This entry was posted on Friday, May 29th, 2009 at 7:00 am and is filed under Advanced Care. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.