Friend or Foe Friend or Foe

TRISTAN LOUGHER B.SC. Part 3 DIGITAL IMAGES BY THE AUTHOR

his instalment in the series Fig 2 will centre on the the Fig 1 TCnidaria, that is the anemones, corals and their allies, the vast majority of which the reefkeeper can view as a bonus when they arrive in association with live rock or specimen pieces of coral. We will also have a quick look at a closely related group that is represented by a common that has caused great consternation to aquarists due to its bizarre feeding apparatus! The Phylum contains over 5000 species – the classes is the little recognised Hydrozoa. majority of which are marine. Their name is Hydrozoans show a wide variety of derived from the unique cells that they can structures and range in size from extremely the U.K. Recently some specimens of possess called cnidocytes. These are home small – (< 2mm) to extremely large (several Distichophora (Figure 3), a purple to the stinging organs that are so obvious in metres across). They range in form from branching variety, have been imported from anemones and jellyfish but hard and soft simple “button polyp” – like to the Indonesian waters and sometimes Millepora corals can possess them too. complex Portuguese Man o’ War (Physalia (Figure 4) can be found for sale as a We can further divide the Cnidaria into sp.). specimen piece. But it is the arrival and separate Classes of interest to aquarists, The life cycle of many hydrozoans identification of hydrozoans as hitch-hikers namely: incorporates a medusa stage. The medusoid on live rock and associated with hard and Scyphozoa Jellyfish stage can be a means for hydrozoans to soft coral specimen pieces that we are most Anemones facilitate sexual reproduction – there are interested in here. Hydrozoa Hydroids / Fire corals separate egg and sperm carriers, or In my experience, Millepora is a very (Millepora sp.) dispersal – the medusoid stage is free common import, particularly with swimming and enables the to Clavularia and Anthelia specimens (so- Hydrozoa distribute its genetic material over a wider called star polyps). It can be very desirable The class which seems to demonstrate range. The medusae are often mistaken for as large specimens can resemble branching characteristics of all of the above named jellyfish and understandably so since they or leafed true hard corals. Figures 5 and 6 have a bell shaped show some Millepora a day after upper body usually importation when the hair-like polyps have with dangling not extended but the colouration and shape tentacles. See the of the colony are typical. Figures of Care must be taken with Millepora as Cassiopea the common name for the suggests. (Figures 1 & 2), a Fire corals can be dangerous for humans true jellyfish, for a producing a nasty rash when coming into better idea of the contact with soft skin. They can also cause overall shape of a problems to fish if placed in flow that is too medusa. strong or direct. Polyps can be ripped free Hydrozoans of the coral in this situation and as they are only float they continue to be capable of stinging infrequently anything they come into contact with – Fig 4 offered for sale in including fish!

28 • MARINE WORLD – FEBRUARY/MARCH 2002 Friend or Foe

Despite this, will become reacquainted in a Millepora can make an week or so! excellent freebie in the reef aquarium and give Scyphozoa- the vital clues as to the correct positioning of the jellyfish specimen piece on which I know that many of you it arrived. All species of reading this will be thinking “I Millepora from the Indo- have never seen a jellyfish in Pacific, where the my aquarium!” and if every majority of U.K. imports jellyfish resembled Cassiopea come from, are found in (Figures 1& 2) then you could relatively shallow water be right but, like the hydrozoa, (<10m) and in areas of some jellyfish have different moderate to powerful life-cycle stages that can flow. demonstrate a sessile stage Specimens of resembling small polyps or Millepora and tubeworms. The commonest Distichophora are Fig 3 form belongs to the genus unlikely to go unnoticed Nausithoe in which the sessile for long in the reef polyp stage lives in leathery aquarium due to their size and the fact that the area they were collected. tubes up to 20mm tall on the surface of live they have a calcareous skeleton. However The Hydrozoan Class also contains a rock (Fig 9). One reason they thrive in the majority of hydrozoans are very small free-living form of hydroid which is marine reef aquaria is due to the presence and often overlooked. Investment in some capable of reaching plague proportions in of zooxanthellae in their tissues although sort of magnifier or hand lens can reveal a specialised breeding systems where there is they will filter feed and can be found in beautifully delicate new world. abundant food (Figures 8a, b and c). I association with photosynthetic corals that Like Distichophora, the majority of have experienced them particularly in require a lot of supplementary feeding. hydrozoans likely to be encountered are association with seahorse grow-out aquaria I believe most sightings of jellyfish in filter feeders and therefore common around which are kept saturated with food at all the aquarium are due to sessile hydroids the bases of soft corals such as times. This species forms an orange furry producing medusoid stages, Nausithoe Dendronephthyea, Gorgonians and sponges mat where they are abundant although the being one of the most likely origins. It is but also many corals that photosynthesise – colour may be due to their food source possible that if they avoided being sucked suggesting a need for supplementary which is primarily freshly hatched brine into filters that they could grow (they reach feeding of the latter in the aquarium. shrimp nauplii and may differ where other a maximum size of 25-30mm) as the Such colonies often resemble long foods are presented. They also seem to be medusa has photosynthetic pigments too. strands of filamentous algae but closer copper tolerant and their origin is a The polyp stage can reproduce scrutiny reveals very small polyps mystery. They could come with the brine asexually which explains the large scale sometimes less than 1mm tall. Often these shrimp eggs or in the artificial salt mix; in coverage experienced by some aquarists. hydrozoans are brightly coloured – yellow, either case they have to be capable of The only jellyfish that is regularly kept red and orange forms are common. surviving complete desiccation! by aquarists is Cassiopea (Fig. 1). This Of little practical use but of general The only way to eradicate these pests fascinating creature is available for sale but interest is the presence of hydrozoans on is by thorough cleaning, which is is not suited to the typical reef aquarium as animals such as decorator crabs or spider something that most breeding and grow-out there is usually too much flow present. crabs suggesting the of environment in systems demand anyway. You just have to These animals are found in shallow lagoons accept the fact that you and the hydroids

Fig 5 Fig 6

MARINE WORLD – FEBRUARY/MARCH 2002 • 29 opinions here Fig 8a Fig 8b but they are based on good solid experiences – both mine and those of my customers. Firstly, I would like to state my opposition to the control of using fish. Two Actinaria – the species have been regularly cited in the anemones literature as capable of controlling glass anemones: The Copperband (Chelmon on sandy or mud substrates and Fig 8c rostratus) and Sunburst ( kleinii). mangrove areas. They have My experience of these fish is that while abandoned the stinging cells that giving the appearance of consuming the jellyfish are renowned for and anemones all they succeed in doing is now their tentacles are full of causing them to remain withdrawn in zooxanthellae. To enhance the crevices. The fish can remove tentacles performance of these symbiotic adroitly and repeated attacks on the algae Cassiopea has evolved to anemones "train" them to stay hidden. rest "upside-down" on the However, remove the fish and almost substrate. miraculously within a couple of days your reef will be overrun with anemones again! Anthozoa Copperband and sunburst butterfly are not really suitable subjects for the reef This class contains the objects of desire for There are two main species that compete aquarium either with their tastes stretching most reef aquarists – the hard and soft for attention within this order. The first is to hydrozoans, colonial anemones such as corals and anemones. We can further the all too common Aiptasia sp (Figures zoanthids and also tubeworms. They will subdivide this class into the orders and sub- 10a and b). This has several common orders which we are most likely to names such as triffid anemone, glass encounter: anemone, glass rose anemone etc. Fossa Fig 10a and Nilsen 1998 state that Aiptasia sp. are Acinaria Sea anemones the most troublesome pests in reef aquaria! Zoanthinaria Colonial anemones Whether you agree with this statement may Corallimorpharia Mushroom anemones depend upon whether your reef is home to Stony corals these persistent creatures or not! Stolonifera Star polyps The main reasons for the proliferation Alcyoniinae Soft corals of these anemones in reef aquaria are firstly that they possess zooxanthellae. This means that the conditions in a reef aquarium with high light intensity provide much of the food they need. However, they are also capable of feeding upon almost any kind of Fig 9 food that is offered to your reef inhabitants NOTE: Tentacles finer – thus supplementing the energy provided than small tubeworms by light. Finally, they are prolific reproducers. Their reproduction in reef aquaria is almost exclusively asexual by pedal fission or budding – this is the main reason for the futility of cutting or grinding out of the pest anemone. Any damage to Aiptasia caused by the aquarist often results in more anemones than were there in the first place. Removal and control of Aiptasia Not an easy one this. I am bound to Nausithoe polyp form experience people who disagree with my Fig 10b

30 • MARINE WORLD – FEBRUARY/MARCH 2002 reduce the overall biodiversity of the anemone with short stabbing thrusts from 5cm peppermints! system and the additional foodstuffs they its front legs. This seems to cause the For those of you that remain require once they have exhausted the anemone to withdraw its trailing tentacles – unconvinced and do not wish to add these aquarium's natural supply can increase perhaps suggesting that the shrimps are very useful creatures to your aquarium why pollutants drastically. susceptible to the stinging cells venom. not establish a "quarantine" system with 6 There is a species of nudibranch which However, once the majority of the tentacles or 7 of these chaps in it? They will exist is regarded as the possible saviour of reef are withdrawn the attack becomes frenzied quite nicely in a 45 litre aquarium with a tanks infested with Aiptasia. Berghia with the shrimp literally ripping pieces few pieces of live rock present and if you verrucornis is a natural predator of glass from the Aiptasia. Very often, in a last bid moderate their food prior to an invertebrate anemones that has been successfully reared to escape, the anemone will release its purchase they will remove any Aiptasia in captivity. I confess to having no foothold but this just enables the shrimp to almost immediately! This type of system is experience with these molluscs as I have carry it off and consume every last piece! I also handy for "cleaning" existing rocks – never been able to source any and this itself have seen small specimens use this as long as they are not too large! is one reason why they are, for the time technique with quite large specimens up to being at least, not a practical solution for 10cm tall. Anemonia reef aquaria. I have spoken at length to Of course I am aware that people have There are several references in reefkeeping members of a couple of U.K institutions had differing levels of success with these literature concerning an anemone that have had some experience with shrimps and for those of you that have tried resembling the common bubble anemone Berghia and received the same opinions and failed to control Aiptasia then there from each. They state that Berghia is a could be valid reasons. If the tank is superb consumer of Aiptasia anemones but being fed a lot of frozen food daily in the fact that they are so specific in their order to keep fish satisfied (perhaps the dietary requirements means they must be reason for the proliferation of Aiptasia in continually supplied with Aiptasia. This has the first place) then the shrimp will tuck- always been a problem with biological in heartily and ignore the more control – the question of balance. The dangerous food option. Sometimes, predator eradicates the pest then dies of simply by withholding such foodstuffs starvation. But at least you've got rid of the from the aquarium for a couple of days glass anemones, right? Well, yes, as long as will stimulate the shrimp to start you never introduce another piece of coral consuming the pests. Given that Berghia or live rock that may be home to Aiptasia! is too specific a consumer of glass In my opinion the peppermint shrimps anemones isn't a shrimp that will eat Fig 13a (Lysmata wurdemanni) (Figure 11) or them but also persist with frozen foods a positive bonus? Fig 13b Fig 11 Peppermints also seem to be reluctant to move great distances in the aquarium itself – possibly a reason why one particular glass anemone persists when all others have been removed. Once final warning concerns the potential for peppermints to consume decorative Parazoanthids – such as the common yellow polyp (Figure 12). I do not speak from experience here as I have a small colony of these polyps in a 1-2cm Lysmata rathbunae are the best display aquarium that is also home to three Anemonia sp. viewed from above. compromise eradicators of Aiptasia. Anemonia is brown in colour These two species are likely to be indistinguishable to the casual observer but Fig 12 as far as I know they both have the same (Entacmea quadricolor) (Figure 13a) in all performance in terms of their ability to but size. Anemonia sp. (Figure 13b) are consume Aiptasia. For the sake of the frequently imported in association with soft article I will concentrate on L.wurdemanni. corals and polyps and reach about 2-3cm This shrimp is classed as a cleaner tall. They are highly mobile and thrive in shrimp by many zoologists but it also has high light and flow conditions. Most of the the beneficial feature of consuming references state that this anemone is Aiptasia. The feeding behaviour can be capable of reproducing rapidly and difficult to witness in aquaria as these potentially overgrowing the entire shrimps are quite secretive and many fish, aquarium. The potential is there as it shares not recognising them as cleaners will the same attributes with regard to feeding actively pursue and consume them if given as Aiptasia. the opportunity. It's no wonder that the The good news is that this anemone is aquarist seldom sees them at all! I have usually highly visible on specimen spent some time watching a group of these invertebrate pieces which can be avoided or shrimps feeding on glass anemones. One the anemone removed prior to introduction individual will attack the base of the to the aquarium. Having stated this,

MARINE WORLD – FEBRUARY/MARCH 2002 • 31 however, I would like to point out that I correctly identify your hard coral. Most haven't received any reports of these require strong light and flow.A good animals taking over aquaria in our region general rule of thumb is that the smaller the but it would be unwise to tempt fate! individual polyp the more light and flow required. For example, large Cynarina sp. Scleractinia – consisting of one large polyp up to several cm across generally tolerate a deeper The Hard Corals position in the aquarium compared to Having discussed the bad guys that can turn Acrapora sp. which is made up of a large up from time to time it's nice to now turn to number of tiny polyps only a few mm in the excellent freebies that the sharp-eyed diameter. aquarist can find in his or her dealers Although the healthiest specimens will aquaria. Close scrutiny of pieces of live inevitably be located on the rocks beneath rock and specimen invertebrates can yield polyps and soft corals that have been several coral species which are rarely imported in oxygenated bags the species imported or very expensive when bought as found in association with live rock can and Fig 20 a specimen piece. Given time and do recover from the transportation process consideration these corals can thrive in and provide some spectacular specimens. Fig 20 marine aquaria. The most common forms on live rock One of the good things about hard include Porites and Favites (Figs 19 & 20). corals is the majority of them are easy to Don't be put off by appearances – if the identify, at least to genus level. The variety rock has been freshly imported then the of polyp form is incredible though and Figs skeleton of the coral will be visible and 14, 15, 16, 17, and 18 all show the variety look pretty dead but given good aquarium on offer. Other common species include conditions will recover in a couple of Pectinia sp., Monastrea sp., Turbinaria sp., weeks. It is my belief that these corals are Heterocyathus sp.and Pavona sp. adapted to quite changeable conditions and Don’t worry too much if you can’t therefore once settled in the aquarium they are able to grow quickly. Figure 19 shows Porites in its green form but it is perhaps make superb selections for beginners – they more common in the brown colour morph. enable them to try a couple of sometimes Porites is often imported on the base very different species at the same time, thus of blue sponge and Nephthyea corals too giving confidence in their system and a indicating that the specimens may have more natural look to the aquarium itself. been found in areas with intense Multi species pieces can also enable illumination and flow. experienced reefkeepers to try specimens that they might otherwise be reluctant to Other polyps introduce. A few weeks ago I located a When I select my specimen pieces I always piece of mushroom polyp that was try to find pieces with more than one spectacular by itself but the rock was also species of invertebrate present. Such pieces home to two small ( 2cm diameter) pieces of Goniopora lobata – a temperamental hard coral that confounds even the best Fig 14 Fig 16 aquarists. Isn't it better to try a small piece like this rather than spend £20-£30 on a larger specimen of this coral? The worst case scenario is that you end up with the mushroom polyp. Careful selection of your next invertebrate could lead to excellent free pieces. Fig 21 shows a piece of mushroom coral that was home to two small cream coloured lumps. Closer investigation Fig 15

Fig 17 Fig 21

Fig 18

32 • MARINE WORLD – FEBRUARY/MARCH 2002 Fig 22 revealed that they were in fact two Fig 25 Tentacles can be separate pieces of Sarcophyton, or over 45cm! leather coral. As you can appreciate, the soft The body of the Platycena corals and other polyps that arrive on is flattened and can be very live rock are, by nature, mostly difficult to spot but the unproblematic. The principles one tentacles, although as fine applies to the reef in terms of as gossamer, are very positioning with regard to correct obvious due to their great lighting and potential for battling length. between species apply to those that are found on the same rock. Transplantation may be necessary at some stage Live rock Fig 23 if the reef is to remain 1 cm in harmony. The figures below show some of the polyps that can be found 2mm together regularly. Medusoid stage buds off from main Phylum Ctenophora colony The ctenophores are a group more commonly known as sea gooseberries or comb-jellies and are found in oceans and seas world-wide. I have included them here, even though they are not Fig 24 cnidarians, as they share many similarities to jellyfish. There is one group that are of interest to aquarists – the Platyctena. Unlike the rest of the phyla they are not free-swimming or planktonic- instead they occupy the surfaces of soft corals and polyps in the aquarium. Sarcophyton and After Barnes 1980 Lobophyton (both "leather" corals) Life cycle stages of a typical hydrozoen, such as the are very commonly home to these ones found in association with gorgonians. The “stalk” unusual animals. The body is very colouration can vary considerably – often being yellow, orange or red rarely seen by the aquarist due to its often transparent nature and flattening. The feature that draws the most attention is the long feeding tentacles that these animals possess. Figure 25 shows a drawing of the tentacles which are very fine and almost translucent. I'm certain that some of you will recognise them! Ctenophores are totally harmless and add to the overall interest of the aquarium. I hope that this latest instalment of the series has been informative and encouraged you to keep your eyes open in both your own aquarium and that of your dealers'. The next article will feature some really bad bad guys and some rather good good guys as it will centre entirely on molluscs. I haven't written it yet – it could be an epic!

Acknowledgements Lisa Birchall for illustrations Matthew Stevenson for editing

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