Skunks, Fires and Peppermints (Oct 2006)

[zanzimog]

Cleaners and Peppermints: Shrimps of the genus Lysmata

The peppermint, skunk cleaners and fire shrimps of the genus Lysmata are possibly the most popular crustaceans in marine aquaria. They can serve a number of useful purposes in aquaria, such as parasite removal, scavenging, or Aiptasia removal, but many species are beautiful and entertaining to watch as well.

Taxonomy and General Biology

Like all shrimps, crabs, lobsters and such, these guys are in the phylum arthopoda, class malacostraca, order decapoda. They are in the family Hippolytidae, along with familiar genera like Thor (sexy shrimp) and Saron (marble shrimp).

In the wild, Lysmata shrimp fall into two broad categories, with rather different feeding, social and reproductive strategies. The cleaner group, which includes skunk cleaners (L. amboinsis, L. grabhami) and fire shrimp (L. debelius) live as pairs and set up feeding stations. Like many other cleaning species, they make themselves conspicuous with their white antennae and colorful bodies.

The other group is generally colored in a red-striped "peppermint" pattern, and includes many species including the "true" peppermint shrimp (L. wurdemani) and others that can be difficult to distinguish from them (e.g., L. rathbunae, L. californica). These duller species live in groups, and are generally nocturnal scavengers, but are known to act as cleaners as well. The photo below shows the true peppermint shrimp, L. wurdemani (Photo credit, Lobo.)


Care and feeding

Lysmata shrimp are extremely hardy in the aquarium, contributing to their popularity. Although they are said to be sensitive to sudden changes in water conditions, their only requirements are decent water conditions, some caves to hang out in, and the lack of predatory invertebrates or fish.

Peppermint species do well in groups, while skunk cleaner species will thrive as pairs or small groups. There is evidence that fire shrimp can get murderous with numbers more than two, or if pairs are disrupted, so it is probably best to keep them as established pairs.

In my experience, mixing cleaner and peppermint species works just fine. They live in different parts of the tank, and tend to ignore one another entirely.

Feeding is easy. I have never seen a Lysmata shrimp turn down anything, including frozen foods, pellets or flakes. The appearance of food usually brings on a frenzy of activity by the shrimp, with peppermints runing from their hiding places, and cleaners even grabbing food from aquarists' hands.


One unstoppable myth (if it is one) is the role of iodine in shrimp molting. Despite the persistant claim that crustaceans need iodine for the molt, I cannot find a reference in the scientific literature that supports either the need for iodine in the molt, or the induction of precocious molts by excess iodine. My offer of $10 for a citation from a peer-reviewed journal still stands.

Reproduction

If one does a literature search for Lysmata, the vast majority of references have to do with their unusual reproductive strategy. For all species in the genus, small specimens are male, which then develop into simultaneous hermaphrodites with fully developed ovaries and a small amount of testicular tissue. Although males changing into females ("protandrous hermaphroditism") is not unusual among shrimp species, changing into a stable hermaphrodite ("protandrous simultaneous hermaphroditism") is quite rare. Adults can act as fully functional males and females, but not at the same mating event. Newly-molted animals act as females, and are fertilized by shrimp that are not molting and act as males.

The strategies for dealing with this differ between peppermint and cleaner species. Peppermint species live in large mobs, and basically wander around until they blunder into another member of the group that is ready to mate. In this case, being a hermaphrodite really does double your chances of finding a date.

Cleaners live in pairs, and appear to alternate molts so that one member of a pair is ready to be male after the other molts.

The eggs are glued to the pleiopods on the bottom of the abdomen, and are kept aerated and clean by the movement of the pleiopods and the attention of the parent's cleaning appendages. Larvae are planktonic zoaeae, which require constant, gentle water motion for survival, and can accept newly hatched brine shrimp as a first food. L. wurdemani is relatively easy to rear, and is being raised in commercial quantities. Cleaner species appear to remain longer in the planktonic phase before settling, and are not being raised commercially at this point.

In the home aquarium, the larvae are an additional source of planktonic food for the rest of the tank's inhabitants, so you may as well think about getting a pair or small group if you plan on getting a Lysmata shrimp.

Aiptasia Control

Peppermint shrimp are known to prey on the pest anemone Aipstasia, making them a welcome addition to most reef aquaria. I have not seen my peppermints eat Aiptasia, but I have always had them in my tanks and the few Aiptasia I have seen have quickly disappeared. The lore (which may be true) is that peps will quickly eat small individuals, and take their time with larger anemones.

One consideration in using peppermints is that there are some very similar species that occur in the same collecting areas of the Gulf and Caribbean, some of which are more destructive than others. The true peppermint, L. wurdemani, appears to be well-behaved, whereas a similar species, L. rathbunae, can be a ravenous little monster. The one pictured below is rathbunae, which is a deeper red and differs from wurdemani in its tail structure. One easy way to be sure you're getting wurdemani is to get them captive-bred


References

Bauer, RT (2006) Same sexual system but variable sociobiology: evolution of protandric simultaneous hermaphroditism in Lysmata shrimps. Int. Comp. Biol. 46:430
Calado R, Narciso L, Morais S, Rhyne AL, Lin J (2003) A rearing system for the culture of ornamental decapod crustacean larvae. AQUACULTURE 218:329
Fiedler, GC (1998) Functional simultaneous hermaphroditism in female phase Lysmata amboinsis (Decapoda: Caridea: Hippolytidae) Pac. Sci. 52:161
Rhyne AL, Lin JD, Deal KJ (2004) Biological control of aquarium pest anemone Aiptasia pallida Verrill by peppermint shrimp Lysmata risso. J. SHELLFISH RES.23:227
Kirkendoll, A. How To Raise & Train Your Peppermint Shrimp. 128 pp. Lysmata Publishing.