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Opae-ula have been observed in ponds at densities at over 500 per square foot! But the total population includes an equal or larger quantity that are in the water table under and around the pond! At times they all are visible and the bottom of the pond appears red! At optimum, it is estimated that a 1,000 square feet pond can have a total population of one million opae-ula! Such healthy ponds were sustainably harvested by native Hawaiians to yield a significant number of opae-ula for use as bait in various forms of fishing. The number can be enlarged by increasing the amount of food available and/or by providing supplemental food. Knowledge of the reproduction cycle is needed for creating mass culture systems or to effectively harvest from ponds on a sustainable basis.
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1. MOLTING. For a short time after molting, a female can receive a sperm packet before a new shell develops. We believe females molt and can reproduce more than once per year. A single isolated female has been observed to molt five times in three months. Larvae and juveniles are known to molt often as they develop. A large amount of molting and the apparent disappearance of a large number of creatures preceded the appearance of juveniles a month or so later. Opae-ula molt as part of their development into larval, post larval, juvenile, and throughout their adult lives. They will eat the molt shells in a day or two. |
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2. EGGS. No berried female has ever been observed in the natural anchialine ponds. Probably due to being fed and with a sense of security, berried females have been observed in aquariums. Ten to fifteen eggs are carried in the swimmerets below the large muscular tail. The swimmerets circulate water around them. When eggs are aborted early, they do not hatch. Larvae that have survived were almost fully formed and were already moving while still attached to the female. Having suitable dark "birthing nests" is necessary. The brood period is between 30 to 38 days. |
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3. LARVAE. Larvae are about 1/8". Their eyes are large and the appendages are not developed. They bob about with their tail pointing upwards and with legs swirling and movement like little helicopters. The larval stage lasts 13-15 days. Adults are not cannibalistic and in larger tanks will generally ignore them. Most of those that hatch into larvae progress to become juveniles and adults. This is significantly different from most other crustaceans that have a lot more eggs but with only a tiny number of larvae surviving. |
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4. POST-LARVAE. Once into the postlarval stage, swimmerets are sufficiently developed to allow swimming horizontally. Up to this stage, a yolk sack sustained them. Now they begin feedin. The tend to hide amongst the rocks a lot. After a while they begin to feel secure and venture out more often. Actual body length has not changed much. The head is proportionally large and the tail still undeveloped. In a few weeks all appendages develop, they enter the "juvenile" stage where they appear as miniature replicas of adults and this is an increase in the growth rate. |
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5. JUVENILE. The photo was taken when the juvenile was about seven weeks old as it was approaching the form of an adult. Antennas are still half its final length. Feeding is especially important at this stage to avoid stunting. When fed, at seven weeks, juveniles measure almost one-fourth inch, or about half of a full-grown adult. Beyond seven weeks, growth is steady until they achieve full adult size in about a year. |
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ADULT. A dime is about 3/4-inch in diameter. A full size fully grown adult
Micro-Lobster is about 1/2-inch. Young juveniles are about 1/4-inch. At times in nature,
they cluster very tightly together and completely cover the surface! Learning the
characteristics of each stage of the Micro-Lobster lifecycle has already given us a lot of
clues to create mass cultural systems. The low nutritional value of the algae that grows indoors is inadequate for opae-ula to retain their natural size and activity level. When not fed in opae-ula jars, they leave a larger shell while molting and a new smaller shell hardens. They effectively shrink. Proper feeding is crucial if the opae-ula are to retain their full natural size and exhibit their active sociable personalities. |
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, it 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 |
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