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ADVICE REGARDING EGGS & LARVAEFuku-Bonsai is serving as a clearinghouse of this type of information and the information on this page will continually change as new information becomes available. Everyone is invited to email and/or send photos to share with others. We don't know everything but are learning more each month as reports come in from customers and research associates. Here's a summary of what we know:
1. OPAE-ULA EGG STAGE: To date, in natural anchialine ponds, no berried female (female carrying eggs) have ever been observed. We believe the natural instinct is to stay in the safe underground hypogeal environment. However, possibly due to confidence that they are no predators in our breeder tanks, the sightings of berried females are increasing. This may also be due to our opae-ula being conditioned to come out to surface-feed on the spirulina. Opae-ula are small and initially it is difficult to spot berried females. They can be most easily seen when they are "swimming laps." Notice that there is sometimes a black spot in the "head area" and this is normal. But sometimes you'll see a swimming opae-ula with two spots with the second spot in the middle of the "tail" section. That's the egg mass! Check it out with the loupe and enjoy observing the reproduction process!
2. FLOATING EGGS: Small floating "blackish" eggs were reported spotted when we shipped units to a retailer. Apparently, a berried female was hiding in the landscape rock and we did not spot it. The tank was sealed and dark for several days as the shipment was not immediately opened. The eggs may have been released by the female. The next morning all floating eggs hatched, but the unit was sold and we could not observe the next stage of development.
3. BROOD PERIOD: Initially, eggs are a bright red-orange and become darker and brownish-black when they are ready to hatch after about about 38 days. Eggs that are aborted or fall off early do not hatch. Almost all eggs that stay on the female to within 3 days of hatching will likely hatch. Females have been observed "kicking off" eggs that were already in the process of hatching. Almost all eggs that hatch go on to mature into post-larvae, juveniles and adults.
IMPORTANT NOTE: No berried female has ever been observed in natural anchialine ponds and all observations of berried females have been in hobbyist or laboratory researcher's tanks. There seems to be a correlation between sighting berried females and later seeing first larval stages, OR, not seeing either berried females or larvae and first noticing very small "post-larvae or very young juveniles" that are initially not very active and which tend to hide in the rocks. We are increasingly receiving a number of email notifications about spotting post-larvae or very young juveniles but not berried females or larvae. I would appreciate an email notification from customers who observe either type of reproduction to gain a larger scale sense of the ratios of each type being observed. Email to: david@fukubonsai.com MAHALO! ~~~David
4. LARVAE STAGE IN LARGE REPRODUCTION TANKS: When hatched, the swimmerets and appendages are not yet fully developed and functioning. They are only about 2.5mm (about 1/8") and seem to hover with head down, tail up, and legs swirling. The first day, movement is very jerky but control improves over the next several days. During this stage that lasts 13 to 15 days, the larvae are living on their yolk sack and no food is necessary. Thomas Iwai reports that the yolk reserves are substantial and that if the larvae had stayed in the cooler hypogeal environment, that they may not need any additional food until they emerge as juveniles! In larger 10 to 15-gallon aquarium tanks containing 100 to 500 opae-ula, there is a very generous amount of space and the free-swimming larvae seem to gather in the upper parts of brightly lit tanks. Sam Gon of Nature Conservancy of Honolulu has been breeding opae-ula for a number of years and was very generous in sharing his knowledge and experience. Go to SAM GON'S PAGE to see his setup.
5. LARVAE STAGE IN FUKU-BONSAI BREEDER TANKS. Our 1/2-gallon and 3/4-gallon units are nice sizes for enjoyment on desks and are designed for high success even with a larger density population. While smaller than tanks normally used for reproduction, our gravel and feature rock habitat seems to be sufficiently effective to have reports of breeding success. But with a lot of lap-swimming activity, the tiny larvae seem to continually bumped by adults. We believe that opae-ula do not have strong visual capabilities. This was initially noticed by Honolulu hobbyist David Chung. He used an inexpensive clear plastic box measuring 2 1/4" x 2 1/4" x 6" tall as a "nursery". He transferred enough water (and the larvae) from the main tank to make it 2" to 3" high in the small box and added a little distilled water every so often to bring the water level back up. He also added a few of the 1/2" size gravel rocks to introduce needed bacteria into the nursery tank. David holds the record in having observed 10 larvae hatching in his 1/2-gallon Introductory Mini-Breeder Tank and after transferring them to the "nursery", having all 10 survive to adults! Go to David Chung's page to review his observations.
6. POST-LARVAL STAGE: After about two weeks in the larvae stage, the swimmerets become sufficiently developed to allow the larvae to begin swimming right-side up and horizontally like the adults. Although they look like miniature adults, their appendages are not yet fully developed. There are scientific standards of when a post-larvae begins to be called a juvenile but it is not as clear-cut as between the larvae and post-larvae stages. Young opae-ula tend to congregate in places that have some organic matter and it is believed that may be suitable food for this growth stage. It is believed that no special food is needed. Post-Larvae and early juveniles tend to hide in the rocks a lot. In time they begin lap-swimming and are noticed as they may be half the size of adults.
| CONCLUSION & SUMMARY
Opae-ula, the Hawaiian Red Anchialine Pond Shrimp (Halocardina rubra) was
scientifically identified by L. B. Holthius as recently as 1963. There are only a few
published papers about them and there has been a lot of new knowledge gained in the past
year. The Fuku-Bonsai Micro-Lobster website already contains the largest amount of
resource information and with the participation of our customers, aquaculture researchers,
and others, the website continues to grow. Everyone is invited to share their observations
and to participate in the research being coordinated by Fuku-Bonsai.
On May 3, 2004, David Chung of Honolulu spotted a berried female and began a detailed daily journal. On June 3, 2004, the first egg hatched! The day-by-day narrative report by David Chung includes photos. *** Go to David Chung's Page |