Spiny Lobsters: Unusual Marine Inverts

Author: Edward Adam Jackson

Large and demanding, spiny lobsters are not for the casual aquarist, but they make beautiful, fun, and long-lived aquarium residents for those willing to dedicate a setup to them.

Rock and spiny lobsters of the genus Panulirus aren’t generally recommended for the mixed reef/invertebrate or fish-only display (with some exceptions), but given a dedicated tank and proper care, these animals are quite worthy aquarium specimens that can make fun displays. Just be sure to know what you’re getting into before making a purchase, as these lobsters are often the victim of impulsive buying habits.

Spiny Lobsters

Over 20 different species belong to the genus Panulirus, and their distribution ranges quite widely. Species of this genus can be found in a wide array of climates, including but not limited to the tropical Pacific Oceans in Hawaii, temperate Pacific waters such as California, and even as far as the Atlantic subtropics in the Caribbean.

The main feature that differentiates Panulirus lobsters from other lobsters is the lack of the large claws (chelipeds) found in their cousins such as Homarus spp. and Astacoidea spp. Not to be outdone, Panulirus lobsters boast a large pair of walking legs in place of the missing claws. They also harbor a pair of antennas that are specialized for sensory perception to help them detect and adjust to their surroundings. These are normally kept alongside the body and extended only when in use.

Panulirus are in large part nocturnal, taking refuge in caves, crevices, and overhangs during the day and feeding and hunting during dusk, early morning, and nighttime hours. Though individuals can be found relatively close to each other at times, lobsters are generally intolerant of each other, excluding a very interesting, seemingly ceremonial gathering that occurs in an Atlantic species, P. argus.

Not a Genus for Casual Aquarists

I find it very sad to walk into various fish stores and see multiple spiny lobsters. As hardy as members of this genus can be, they simply are not suited to the average home aquarium. The list of compatible organisms is quite short and arguably non-existent for some individuals. Furthermore, most aquariums are too small to house these organisms, some of which reach sizes upward of 2 feet.

Overgrown

These overgrown lobsters are quite indiscriminate in what they will eat and should be the poster child for that popular hobby phrase “opportunistic omnivore.” Any invertebrates, sessile or motile, are at risk, and the clumsy movements of these animals can topple unstable rock fixtures or decorations. And yes, even slower, smaller fish are at some risk with a large lobster in the tank. They should by no means be classified as social or reef safe.

A Big Mess

As with most lobsters, rock lobsters are quite messy eaters and big waste makers. Since they are crustaceans, it’s necessary to keep dissolved organics to a minimum. Given their large size, eating methods, and waste production, a lobster’s bioload on a system could easily rival that of any similarly sized or larger predatory fish, or one that has a high metabolism. The nutrient accumulation caused by these animals alone can cause the balance of smaller, unprepared systems to take a negative turn.

I admit that this causes Panulirus spp., and lobsters in general, to seem undesirable when there are other smaller, more compatible crustaceans that can coexist with other invertebrates and fish. A tank with lobsters would certainly need to be designed and maintained with them as the centerpiece, something many aquarists just aren’t willing to do.

Selection

Many species of spiny lobsters are placed in the “best left in the ocean” category. Living in Southern California, one of my largest complaints is the fact that many stores offer local specimens, which are temperate. If you plan to place a temperate species, such as the California spiny lobster (P. interruptus), in tropical water, you are condemning it to death.

Temperatures

Animals like P. interruptus do best in temperatures around 60°F—temperatures above 65° are pushing it. In fact, while diving mostly off of Catalina Island during the summer of 2011, most temperatures for the month of May varied from 58° to 64°. The highest I measured was 66°, and that was during high noon in a tide pool less than 5 feet deep.

Water Chillers

If you decide to keep one of these temperate species, a water chiller is a must. These units can be quite expensive. Temperate tanks also tend to constantly form condensation on the outside due to the ambient temperature in the room typically being higher. To counteract this, a thicker and preferably acrylic tank would be the best way to go. As such, it would probably be in your best interest to keep tropical specimens. The following list includes the members of the genus that aquarists are most likely to come across.

Ula (Panulirus marginatus)

P. marginatus, known locally as ula, is endemic to Hawaii. The species itself is highly protected, as are all the animals in Hawaii, and it will be quite difficult to attain one. Any commercial gathering is currently illegal; only hand-caught ula over certain lengths are legal.

Having said that, they are beautiful creatures that are very hardy when given the right care. As with most lobsters, they are quite voracious eaters and will easily consume any invertebrate or plant life housed with them. Tank lighting and rock arrangement will need to be thought through very carefully, as this animal is a dedicated nocturnal reef denizen. This species reportedly attains lengths of 18 inches, though 12 inches is much more common.

Blue Spiny Lobster (P. versicolor)

In my experience, the blue spiny lobster is the most widely available species in the aquarium trade. It’s also a tankbuster at a potential 24 inches. They are much more predictable and agreeable than their cousins, especially as juveniles. For the most part, they are fairly timid and calm—at smaller sizes, it is not unheard of to hear of them cohabiting in mixed reef tanks even with other lobsters, causing no harm. Though they are more timid than most lobsters, they can still be quite boisterous and destructive as adults, so my recommendation stands to keep this species and all spiny lobsters in dedicated aquaria.

As it grows, the blue spiny lobster will begin feeding indiscriminately with a seemingly bottomless stomach. It should be fed various meats of marine origin. Blue spiny lobsters appreciate overhangs and caves in which to hide, though it is commonly seen burrowing pits into the substrate to take refuge. Overall, P. versicolor is quite hardy, has lots of personality, and in general is just a fun pet. As it adjusts to captive life, it can be coaxed into exploring its environment during daylight hours.

Ornate Spiny Lobster (P. ornatus)

The ornate spiny lobster has quite a large distribution in comparison to some of its cousins, ranging from the Red Sea all the way down to Africa, and is a common sight in many Western Pacific islands. Quite boisterous and very bold, it will ruthlessly defend its territory. Though lobsters are destructive in general, the ornate takes the meaning to a whole new level. This species is yet another tankbuster, with a potential length of 24 inches. It is best kept as a single specimen.

Spotted Spiny Lobster (P. guttatus)

The spotted spiny lobster is quite a handsome specimen and, aesthetically, my favorite of the genus. This is one of the few spiny lobsters you will find in association with sessile invertebrates. It’s quite common to see the spotted spiny lobster taking refuge among overhanging coral rather than a rocky cave. It also appears to be somewhat more reserved and cautious than other spiny lobsters, beingquite difficult to coax out in daytime hours. Its potential size is somewhat more manageable at 20 inches, though 12 and 16 inches are common.

Hawaiian Blue Lobster (P. penicillatus)

The blue spiny lobster, or Hawaiian blue lobster, (P. penicillatus) is another species that is routinely available in the aquarium trade. Though not indigenous, it’s most common in the Hawaiian Islands and falls subject to the same laws as P. marginatus. The laws are just, as this animal has been irresponsibly overfished.

Its behavior is very similar to that of P. versicolor, but this species comes in a slightly more agreeable size, with adults rarely growing to 15 inches in length. It’s less prone to scavenging organic matter than the other members of the genus and is more likely to seek out live prey—something worth noting.

Caribbean Spiny Lobster (P. argus)

Commonly known as the Caribbean or Florida spiny lobster, P. argus, as its name suggests, hails from the subtropical Atlantic, even as far as the Gulf of Mexico. This too is quite an attractive species, with a striped body that flaunts brown, gray, and even some yellow pigmentation.

It’s more predator than scavenger, commonly hunting sea urchins, mollusks, other crustaceans, bivalves, and even the occasional fish. Studies of carcasses have revealed a significant amount of vegetable matter in the stomach, so some sort of plant matter should supplement its mostly carnivorous diet.

Like P. ornatus, this species can be quite bold and aggressive. Tankmates are once again not advised, though similarly sized specimens do appear congregating in reef overhangs, so it may be possible to care for multiple individuals in the same system.

The Ceremony

As I mentioned before, P. argus also engages in another unique social collaboration: The ceremony starts with a small gathering in shallower waters just before the dreaded storm season. Once the individual congregation gains numbers, the animals march together in a very orderly line into deeper water. Logical guesses lead scientists to hypothesize that the march into deeper water is a response to the heavy tropical storm systems that pound the area for a significant duration of the year, and that the sudden social behavior of these quite anti-social creatures is a defensive mechanism. It is quite an odd but very eerily beautiful sight I hope to see one day in person, but for now, you can check out a video of it on the Aquatic Videos blog.

California Spiny Lobster (P. interruptus)

The California spiny lobster is a temperate species with a range along the coast in the Eastern Pacific Ocean. It hails from as far north as the Bay Area down past Baja California to the gulf of Tehuantepec, Mexico. Its channeled or interrupted slots and grooves go across the abdomen in the tail section, something that is not as prevalent in other spiny lobsters (which have uninterrupted grooves or lack them completely).

It is in large part nocturnal, emerging at the end of dusk to feed on echinoderms such as the California purple sea urchin (Strongylocentrotus purpuratus) and smaller ochre sea stars (Pisaster ochraceus) as well as mussels, clams, smaller crustaceans, and dead or dying organic matter of any kind.

It can grow up to 30 inches in length, though 12 to 16 inches is much more common. Older males can weigh as much as 25 pounds. There are strict regulations placed on commercial and private fishermen, as this animal takes 5 to 10 years to reach sexual maturity—at which time it reaches only a mere 2 to 4 inches at best.

These lobsters are an integral part of the kelp forest food chain, keeping the urchin populations in check, thus helping kelp grow. They also serve as food to many animals, including marine mammals in the area as well as California’s large resident sheepshead wrasse (Semicossyphus pulcher). Though there are mixed reports of their lifespan, most seem to concede they are capable of living up to 50 years, during which they never stop growing completely.

As noted, chilled water is a necessity for these temperate animals, as they inhabit water in the mid-50s to occasionally the low 70s in extreme weather cells. I prefer to pick a number and keep it as stable as possible; Panulirus under my care are usually kept from 60° to 64°. You are more likely to see live specimens in the fresh-seafood section in your food market than an aquarium store, which is likely for the best, as this is the main species of this genus too often sold to reef/tropical aquarists.

Choosing a Tank

Now here comes the fun part. Once you’ve decided that spiny lobsters are just so neat that you can’t live without them, it’s time to design an appropriate setup.

These animals need quite large tanks, and surface area is of optimal importance. Generally speaking, an ideal setup would have the width of the tank being at least 1½ times or, even better, twice the length of the animal. The length of the tank should also be at least 2½ times the length of the specimen.

Unlike many of the other animals we care for where surface area is a must, the height of the aquarium can be factored into usable area. Despite being clumsy, Panulirus are adept at climbing rocks, so sturdy overhangs can be used to create a stunning display. Total water volume for a fully grown lone specimen should be a minimum of 75 gallons, with 100 and 120 gallons being better choices. Again, due to the behavior, these do not have to be standard aquariums. Taller cylindrical aquariums that can be viewed in 360° with hiding/climbing centerpieces can really put the specimen in the spotlight so to speak.

Filtration

As I mentioned earlier, the waste produced by a lobster can rival that of larger, predatory fish. While lobsters generally are a hardy lot, they are still invertebrates and water conditions need to be kept pristine at all times. The water volume should turn over 10 times per hour at minimum, with more turnover being preferable. An oversized and efficient protein skimmer is also a must in the lobster system. I would also consider employing the use of a macroalgae refugium for nutrient export.

Lighting

In a dedicated species-only tank, there should be no need for high-intensity lighting. Nearly anything will do. Normal-output T-5 fluorescents are more than sufficient, but if you want to bring out the colors in your specimen, very-high-output T-5 fluorescents or LEDs (due to their adjustability and longevity) would be my aesthetic choice.

Since lobsters are nocturnal, I would use a higher Kelvin rating (14,000k to 20,000k) to make the specimen comfortable and possibly encourage daytime activity. Red lights and moonlights are other viable options for viewing these creatures of the night. Moonlights are often included as options in many of the newer eco-friendly LED units as well.

Temperature Controller

Depending on the needs of the individual specimen you keep, and the ambient temperature where the system is being held, heaters and/or chillers may be necessary to keep the water at the desired temperature. As with any aquarium specimen, the proper temperature for the animal should be targeted and held stable to the best of the owner’s ability.

Live Rock, Aquarium DÉcor, and Substrate

DÉcor

As beautiful and majestic as these creatures may appear on the outside, inside lies a clumsy and destructive (whether it be on purpose or not) animal. Lobsters also need a lot of area to roam, so dÉcor and live rock should be kept to a minimum.

Caves, overhangs, and similar types of structures should be stabilized with some type of media, such as a PVC frame or epoxy. Any loose items or structures could be easily toppled, and you could possibly end up with a crushed lobster. Lobsters that have just molted are particularly sensitive and vulnerable, and sharp, protruding objects should be avoided at all costs.

For aesthetic reasons, I would design any potential hiding areas, caves, and overhangs to be viewable even when the animal thinks it is out of sight. With a design like this, you will be able to view the animal even when it is attempting to be reclusive. The goal is to allow the animal to feel secure but still be able to enjoy it.

Substrate

As for substrate, many spiny lobsters will often burrow to take refuge rather than go to the nearest rocky cave or overhang. To allow the lobster to perform this natural behavior, the substrate will need to be quite deep, around 6 inches. Lobsters also prefer coarse media and not oolitic sand, which has become so useful and popular in reef aquaria.

With the coarse media and the lobsters’ burrowing capabilities, a true deep sand bed will become difficult to maintain in the display. I recommend weekly cleaning and vacuuming of the substrate to deter detritus accumulation. Should you wish to employ a deep sand bed, I suggest doing so in a dedicated refugium. On the same note, since dÉcor must also be kept at a minimum, you can also place any extra live rock in the refugium to serve as a breeding ground for beneficial microfauna and nitrifying bacteria.

System Maintenance

As with any aquarium, regular maintenance of a lobster system is key in keeping things stable and running smoothly. The tank’s parameters should be kept close to seawater levels. Weekly (or even more frequent) testing of the water parameters is mandatory. As I’m sure you know, ammonia and nitrite should always be at zero. Since a lobster is an invertebrate, you should attempt to keep nitrate as close to zero as possible, though a level of 10 ppm is acceptable.

The pH should be kept stable between 8.2 and 8.4. You can make this easier by maintaining high calcium levels (300 ppm to 450 ppm) and proper alkalinity levels between 8 and 12 dKH. In conjunction with the filtration system mentioned above, weekly water changes should be performed and detritus should be siphoned/vacuumed from the dÉcor, rockwork, and substrate. Salinity should be maintained between 1.024 and 1.025.

General Lobster Care and Feeding

Aside from the standard time and effort involved in keeping a marine aquarium, here are some special notes as far as lobster care goes.

Molting

As with all crustaceans, lobsters go through the process of molting, shedding their exoskeleton in order to grow. During and after this process, the lobster is very vulnerable to predation because it loses much of its protection in the molting process, The new exoskeleton is soft and requires time to harden.

Lobsters are more likely to be eaten or picked on in the wild in this state and will remain rather reclusive for several days following the event. Likewise, if you’re keeping multiple lobsters or other crustaceans in the tank with the lobster, they may attempt to attack a freshly molted specimen.

I do not recommend removing the newly molted animal, as the process is stressful enough. Instead, utilize a piece of egg crate, starboard, or acrylic as an in-tank divider to protect the animal until it can defend itself again. The process of molting, which is often taken for granted by aquarists, is quite stressful on the animal. Honestly, it’s amazing they even make it from a planktonic pelagic stage to their more familiar form.

Feeding

As far as feeding, these animals have a varied diet that you should attempt to duplicate as best as possible. Plan to keep at least five to six different foods on hand at all times and alternate between them. Utilize meat of marine origin, including (but not limited to) fresh market fish, scallops, clams, oysters, shrimp, krill, and squid. Some vegetable matter is necessary, such as spirulina, nori (dried seaweed), fresh algae(s), and even dry fare such as sinking wafers or pellets.

For enrichment, both nutritionally and mentally, offer your specimen some of its invertebrate food (such as bivalves and echinoderms) with the shell still intact. In fact, I have seen nutritionists in public aquaria routinely offer panulirids live sea urchins (after proper quarantine).

Occasionally soaking the foods in calcium or a beta-glucan supplement isn’t a bad idea. After molting, do not immediately remove the abandoned exoskeleton, as the specimen may attempt to consume it to some degree. Consuming their old home may be a way for them to regain lost calcium and various nutrients lost during the process.

Compatibility

As mentioned many times previously, the list of tankmates these lobsters can be kept with is short, though with a large-enough tank and hiding places, multiple specimens of the same species can coexist. With regard to other invertebrates, I have seen some hardy sessile invertebrates utilized in lobster tanks to add more appeal. Temperate and tropical corallimorphs, such as Corynactis californica (temperate), Discosoma spp., and Actinodiscus spp., can be potentially good choices.

As far as fish go, larger, slower-moving fish that won’t attack the lobster and vice-versa are at times utilized, though not without risk. For example, I have seen P. interruptus often housed with larger, local-to-its-area, gladiform fish such as Gadus macrocephalus. Both largely ignore the other.

Choose Wisely

Hopefully this article has shown you that spiny lobsters are not to be casually included in community tanks or purchased on impulse when smaller and less destructive.

It will obviously take quite dedicated aquarists to set up such an elaborate display for a single specimen, especially with such a myriad of choices in the marine aquarium trade. I think, however, that we are starting to see a trend away from the mainstream, where aquarists are more inclined to adore oddball creatures and set up biotope displays, which I think is a positive.

It gives the hobby more inclusion, expanding options to new or bored aquarists. To each his own; maybe a spiny lobster just happens to fit your persona. Whatever you choose to do, be responsible and care for your animals to the best of your ability. Good luck to you, and possibly your future lobster.

See the full article on TFH Digital http://www.tfhdigital.com/tfh/201212#pg89