Marine invertebrates are prized not only for their colours but their weird and wonderful forms, which are so alien to what is found on land. There are many different marine invertebrates (they make up the huge majority of the diversity of life in the ocean), so which do you choose? How about one or more of the more attractive examples below…

The most beautiful marine invertebrate…

The reason most of us are attracted to this hobby is the sheer beauty of the marine species involved; I often am asked, “What do you think is the best looking marine invertebrate for my tank?” I think for a while then rattle off any combination of the below species (in no particular order of beauty):


1. Harlequin shrimp (Hymenocera Picta):

The Harlequin shrimp looks very cool

The Harlequin shrimp looks very cool

Only the best looking crustacean in the ocean (well…I think it is 😉 with an impressive looking white body with black-rimmed blue splotches all over it; they are indeed one of the most elegant looking shrimp species.

They are peaceful and reef safe and thrive when are fed well and have regular supplements of the same trace minerals hard corals need (especially Iodine for good shell growth). They grow to about 5cm in length and live in pairs feeding exclusively on starfish, especially the Crown of Thorns starfish in the wild

These timid creatures will do well in any sized tank where they are free from harassment and high nitrate/copper levels. Keeping a nano tank centred around a mated pair makes for a cool variant on the typical reef nano theme (as I talked about in a previous Eclass).

They need reef quality water and can be fed on a diet of starfish arms! The easiest way to do this is to grow chocolate-chip starfish (Protoreastor nodosus) or Linckia starfish in a separate tank and every two weeks harvest an arm (which regenerate) to feed your shrimp. Adults may also eat sea Urchins.


2. Sea Apples of the genera Paracucumaria and Pseudocolochirus:

The weird and wonderful Sea Apple - for experts only!

The weird and wonderful Sea Apple – for experts only!

These strange filter feeding sea creatures are highly sought after because of their beauty, interesting behaviour and strange form. They are actually a type of sea cucumber and come from the tropical waters of Australia. A sea Apple feeds on phytoplankton and has a blue, round body and has red feet with multi-coloured tentacles. They can grow to almost 8 inches long.

Watching them fed is interesting as they send their oral tentacles to catch particles of food then retract them into their mouths; like a multi-trunked elephant!

Sea Apples are reef safe (in terms of compatibility) but are not for beginners, this creature will release toxins and/or its internal organs if nibbled on or attacked (usually by typically reef-unsafe fish or crustaceans) as a defence mechanism. Their toxins are potent and can easily kill other marine organisms. They may also release toxins as they die.

If housed without any fish or crabs that may pick at its tentacles Sea Apples can thrive with no problems as long as they are fed daily. Sea apples can easily starve in saltwater systems and require targeted feeding of phytoplankton (in liquid or dried forms).

Sea apples like room to move around and high water current as well as plenty of live rock (from where they get their food).


3. Linckia starfish (Linckia laevigata):

I just like blue Starfish...

I just like blue Starfish…

I first saw these beautiful deep blue Starfish on a trip to Fiji and have loved them ever since. They are often known as the Blue starfish and are reef safe providing a stunning focal point in any reef tank. They can grow to up to 30cm. They have fleshy, tubular arms and are quite firm to the touch.

They enjoy hanging out on sandy bottoms or hiding amongst the rocks and will be a peaceful addition to any tank. They will happily scavenge the tank but also appreciate some meaty foods being placed under them (to stop fish getting it!) from time to time.

Linckia starfish are very intolerant of any quick changes in water pH, oxygen and salinity and must be very slowly acclimated using the drip method. Many specimens die because their acclimation is not gradual enough.

Linckia are prone to parasitisation by tiny snails (Thyca crystalline) so an eye must be kept open for these appearing on the starfish. Many other species predate Linckia like Pufferfish, Harlequin shrimp, Triton shells and some anemones.


4. The Bubble-tipped anemone (Entacmaea species):

Clownfish love these too...

Clownfish love these too…

This anemone is very attractive, hardy and adaptable, its colour morphs range from orange, red, rose to green. Its colouring and tentacle form make it very attractive to many saltwater aquarium owners.

It also hosts the largest range of Clownfish species (13!) and is not a fussy eater nor grows very big (but is still classed as a large anemone). It can grow up to 30 cm in diameter. These anemones do best when they are hosting a Clownfish.

The most popular BTA (Bubble Tipped Anemone) is Entacmaea quadricolor the bubble tip or Rose anemone. BTA’s do best under intense lighting (metal halide or similar), as they are photosynthetic, to make yours truly thrive try supplementary feeding with finely chopped meaty items a few times per week.

BTA’s do have a sting so don’t place too close to corals or other anemones and ensure they have a nice spot to anchor (for example purchase one attached to live rock) so they don’t move around too much.

They are easy to “frag” by splitting yourself (in 4 with a razor blade through the mouth) or naturally and come in colours from tan, green, orange, pink, red, purple. This anemone is easily recognised by the cool looking “bubble” in each tentacle just before the tip. This type of anemone does not often roam around the aquarium, which is nice!

These anemones do well with “reef” minerals such as iodine and the same conditions (water quality and lighting) found in a reef aquarium.

BTA’s are primarily photosynthetic but also benefit from meaty supplementary feeding (less feeding is necessary when hosted by an Anemonefish).

So, that is my two cents worth for what I believe to be the most stunning and most interesting reef aquarium inhabitants!

Marine invertebrates can often be much more colourful and interesting than marine fish, a clever selection of marine invertebrates will make for a stunning, constantly interesting saltwater set-up.

So what do you think?  Are there any major contenders you think I have missed out?