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Cuttlefish Husbandry: Part IV - How do cuttlefish reproduce?<< Cephalopod Articles | Photographs and text by Dr. James B. Wood
You have read parts I, II and III of this article and already know where to purchase a cuttlefish and how to keep one. Now you want to know the hard core details, you want to delve into the sex life and reproductive biology of a creature that has been described as the closest thing we have to a living alien.
Many cephalopods are short lived and only reproduce once. For example, most tropical and semi tropical species of octopus live for a year or so, and the females die after their single brood of eggs hatch. The males also have short life spans. This strategy seems odd to us; people tend to associate long life spans and iteroparity (producing offspring more than once) with intelligence. It seems a waste for something as intelligent as a cephalopod to have such a short life cycle. Mammals, however, are just one of many groups of animals and we should not expect other groups to have the same reproductive strategies that we do.
The cephalopod strategy can best be summed up by the phrase 'live fast and die young', though there are a few exceptions. Sepia officinalis is fairly long lived for a cephalopod, they live for 1.5 to 2 years, depending primarily on temperature. Because of their short life spans, it isn't uncommon for a cephalopod to reach maturity and reproduce in a home aquarium.
OK, let's assume your goal is to mate cuttlefish and produce a second generation. Perhaps you want to help fill in the colossal demand that will surely appear once this article goes to print. Or perhaps you have heard of cephalopods' amazing cognitive abilities and wanted to train a small army of them to do the dishes, walk the dog or buy and sell securities.
The first thing you need is... correct! A male and a female cuttlefish. Adult cuttlefish are hard to sex and the only 100% reliable way to sex a live one is to see it mating or laying eggs. However, a male cuttlefish might aggressively display to a reflection of itself in a mirror. The aggressive display of cuttlefish consists of a vivid zebra stripped pattern, bulging eyes, and often lining up parallel to its reflection. Unfortunately, females will also occasionally do this display. We tried this method and lets just say that the 'flip a quarter method' would likely have been more productive. Another and more effective test, is to put two cuttlefish in a tank that is divided by a clear pane of plexiglass. If one cuttlefish displays the aggressive pattern and rushes head first at the other cuttlefish which is not striped and is brownish in color, you probably have a male and a female. Cuttlefish mate head to head. If you have two males they should both do the aggressive pattern and line up parallel to each other to size each other up. Unfortunately, if you put two males together that haven't grown up together they may fight. They should go through their assessment display first which gives you time to separate them.
Since sexing techniques are far from reliable, the best way to get mated cuttlefish is to raise a group together in a large aquarium. They can tell each others sex by sight and will mate readily when they are old enough to do so. By keeping several cuttlefish you are increasing the chances that you will have at least one male and one female. You will need a very large tank to raise a group of Sepia officinalis to maturity.
Unlike octopuses, female cuttlefish will lay eggs and continue to eat for several months. The large eggs are laid one at a time. My cuttlefish attached her eggs to the airline and incoming water tubing. The female incorporates ink into the egg case when she lays the eggs causing them to look a bit like a cluster of dark grapes. The eggs take approximately 50 days to develop depending on temperature.
Hatchling Sepia officinalis are one of the easiest species of cephalopods to rear. Currently, the National Research Center for Cephalopods has a 14th generation of consecutively lab raised Sepia officinalis. The hatchlings are fully formed versions of their parents at birth and do not go though a difficult to rear planktonic phase like many marine creatures do.
Hatchling cephalopods require live food. While Sepia officinalis is the only cephalopod species that has been reared through their youth on Artemia, I do not recommend using Artemia unless there are no other options as many of the cuttlefish will die and the growth rates of the survivors will be retarded. Mysid shrimp, small marine fish, amphipods, isopods, and other small live marine crustaceans and fish are ideal first foods. Bill Mebane, a scientist at the Marine Biological Lab at Wood's Hole, has had great success using newly hatched killifish (Fundulis grandis, sorry killifish lovers!) to feed hatchling cuttlefish. Killifish eggs can be ordered from Gulf Coast Minnows; their address is at the end of this article. The eggs can be shipped damp, are inexpensive, and are an especially great option for land locked aquarists. Essentially they are the Artemia of the fish world. I've heard that some aquarium stores are starting to regularly offer live amphipods (also known as scuds, hoppers, or beach fleas) for sale; these are the main food I have using to fed my hatchling cuttlefish.
Foods should be 0.5 to 1.5 times the mantle length of cuttlefish. Freshwater fish, fresh water amphipods and fresh water shrimp could be tried if live marine foods are not available. Artemia should only be tried as a last resort.
Hatchlings grow very quickly and will eat a lot of food. Most hatchling cephalopods double their weight every week or so for the first few months. To put that kind of growth rate into perspective, imagine how big you would be if your weight doubled every week! Food quality and quantity are very important at this point. If you have too many hatchlings it would be a good idea to farm some out to friends instead of starving all of them. If you need some friends, I'm sure there are plenty of people on Ceph Group willing to adopt your excess cuttlefish.
Hatchlings can be reared as a group in a small tank, or in a floating container in your main tank. They will associate you with food and take food from tweezers, a skewer or your hand at a very young age. If all goes well, your cephalopods will quickly out grow their rearing containers and you can train them in international espionage and unleash them on the world.
In the last 20 years scientists have learned a lot about the husbandry requirements of cephalopods but unfortunately little of this information has filtered down to aquarists. Because of this, much incorrect or outdated information and advice on keeping cephalopods exits in the hobby; there still are no books for aquarists on keeping cephalopods. Hopefully articles such as this will convince aquarists to consider keeping a pet cephalopod. The common cuttlefish, Sepia officinalis, is an excellent choice for a new pet.
Cephalopod life cycles and The UFAW handbook on the care & management of cephalopods in the laboratory are good books on cephalopods though they are not written for hobbyists. Hanlon and Messenger have recently published an excellent book on cephalopod behavior. All of these books are listed in the references.
Thanks to my wife Deborah and also to Erika Chen for commenting on this publication.
Gulf Coast Minnows, Inc.
110 Bobcat Lane
Thibodaux, LA 70301
National Research Center for Cephalopods (NRCC)
Marine Biomedical Institute
301 University Blvd.
Galveston, TX 77555-1163
ReferencesBoyle P.R. 1991 The UFAW handbook on the care and management of cephalopods in the laboratory. Universities Federation for Animal Welfare.
Boyle P.R. (ed) 1983 Cephalopod life cycles, vol 1. Academic Press, London.
Boyle P.R. (ed) 1987 Cephalopod life cycles, vol 2. Academic Press, London.
DeRush R.H., Forsythe J.W., DiMarco, F.P. and Hanlon R.T. 1989 Alternative diets for maintaining and rearing cephalopods in captivity. Laboratory animal science. 39(4): 306-312.
Hanlon R.T. and Messenger J.B. 1996 Cephalopod Behavior. Cambridge University Press, Cambridge.
O'Dor R.K. and Webber D.M. 1986 The constraints on cephalopods; why squid aren't fish. Vie Milieu 35: 267-271.
Wood, J.B. 1994 Don't fear the raptor; an octopus in the home aquarium. Freshwater and Marine Aquarium Magazine. 17(4).
Articles ReferenceWood, J. B. 1998 Cuttlefish Husbandry. Part IV; How do cuttlefish reproduce? Freshwater and Marine Aquarium Magazine. vol 21, no 10. Reprinted in: The Cephalopod Page. Wood, J. B. Ed.
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