Category Archives: Invertebrates

Latest Posts

The Reef Aquarium After Hours: Four Reasons to Keep That Flashlight Handy

Long tentacle anemone (Macrodactyla doreensis) at night under LED lightingAnyone who has done any night diving knows that nighttime activity on coral reefs is very, very different from what goes on there during the day. A dramatic “changing of the guard” occurs, with diurnal fish seeking refuge in the reef and nocturnal predators and planktivores taking dominion. Parrotfishes, wedged in caves or crevices, cloak their chemical signatures in mucous cocoons. Morays, only partially visible during the day, slither from their dens and swim in the open in search of prey. Octopuses, too, lose their daytime shyness and ply the reefs with busy tentacles. Night-feeding corals that appear bare and lifeless while the sun is up come into their glory with polyps fully extended. Bioluminescent organisms of all kinds put on otherworldly displays

How Much Live Rock Do You Really Need?

The amount of live rock needed in your aquarium is based on several factorsOnce hobby newcomers learn what live rock is and all the benefits it can provide in marine aquariums, the next big question they invariably ask is, “How much of it do I need for my tank?” More experienced fellow hobbyists, eager to be of help, typically respond with a pat answer along the lines of “somewhere between one and one-and-a-half pounds per gallon.” While this type of formula is certainly convenient and eliminates guesswork, it unfortunately fails to address several key factors that must be considered when determining how much rock is actually appropriate for a given system. Here are just a few of them:Differing density Pound for pound, not all live rock stacks up the same. The density of live rock can vary considerably from one type/collection locale to another—and a highly porous rock is going to be significantly lighter than a very dense rock of the same size. (Visualize holding a chunk of lava rock in one hand and an identically sized chunk of granite in the other, and you’ll have the idea.) So, you can expect 100 pounds of highly porous rock to take up a lot more space in your tank than 100 pounds of dense rock will. Livestock objectives How much rock you’ll want to place in your tank will also vary based on your objectives for the system. For example, a full-blown reef tank might require more rock than a fish-only system to ensure there’s an adequate foundation for the various invertebrates you plan to keep.

A Shrimp-ectomy Performed on a Shrimp

Male and female bopyrids. Credit: Sars, 1899

Male and female bopyrids. Credit: Sars, 1899

 Bopyrid shrimps are a diverse and understudied group which are obligate parasites on the bodies of decapod crustaceans (i.e. crabs,shrimps,lobsters). Most make their living occupying the safe confines of the branchial cavity of their host, piercing the delicate gill tissue found therein and imbibing the delicious crustacean blood which pours forth.… More:

The Candy Basslet: A Sweet Deepwater Denizen on Many a Hobbyist’s Wish List

Candy Basslet (Liopropoma carmabi)Ask any group of marine fishkeepers to name their most sought-after species—the fishes they’d really love to own if money and availability were no object—and most of them will likely place the candy basslet (Liopropoma carmabi) somewhere close to the top of that list. Ah, but despite its stunning good looks and very manageable size, L. carmabi, a deepwater species hailing from the tropical western Atlantic and Caribbean, is rarely available in the hobby and fetches a daunting price on the few occasions it is offered for sale. I’ve only ever seen this species in photos and videos (oddly enough, it seldom finds its way into Toledo-area fish stores), but if those depictions are anywhere near accurate, L. carmabi truly is a jewel of a fish. It’s probably all for the best that specimens never materialize locally, however, as I’d probably have to sell my firstborn to afford one.Physical traits Reaching only around 2½ inches, the candy basslet is a relatively diminutive species. But there’s nothing small about its eye-dazzling coloration

Venus Flytrap Anemone

credit: I. MacDonald

credit: I. MacDonald

 This beautiful creature is the Venus Flytrap Anemone, Actinoscyphia aurelia. This anemone can grow up to 12 inches (30.5cm) in length and girth, but the size that it grows to depends largely on the amount of food available. While its body are stick-like in shape, its mouth is rather large and wide, and resembles the plant that it is named after. And, while the flytrap anemone feeds with nematocysts on outstretched tentacles, it does perform the characteristic venus-flytrap-motion as a defensive tactic, further strengthening the resemblance to the plant look-alike.… More:

What Makes Someone a Marine Aquarium Expert?

Being in a somewhat contemplative mood as I enjoy my third cup of coffee this Friday morning, I’ve posed to myself the philosophical question, what does it mean to be an “expert” marine aquarist? In other words, when I write something like, “That challenging species should be kept only by expert hobbyists,” who exactly am I referring to? As I mull it over, I’m coming to the realization that the answer to this question isn’t as obvious as it might seem.Years in the hobby? Is expertise a simple a matter of years in the hobby? If that were the case, someone who has been a hobbyist for 20 years but has never kept anything other than a single ocellaris clownfish would be considered an expert—when in reality, that individual is experienced only in keeping one specimen of a relatively bulletproof species. Further, there are plenty of long-time hobbyists out there who repeatedly exercise poor judgment, never learn from their mistakes, and make irresponsible stocking/husbandry decisions no matter how many years they keep at it. So time in the hobby can’t be the sole answer

What’s Wrong with This (Reef Tank) Picture?

A more reasonably stocked reef aquarium, unlike those portrayed in some advertisements (we’ve all seen them…)Right now, I’m gazing at a magazine ad featuring the image of a reef tank, and the one word that comes to mind is “magnificent.” I’m sure you’ve seen one like it before, but allow me to describe it to you. In this one tank, I can see all manner of soft and stony corals; sea apples; Tridacna clams; mushroom and zoanthid polyps; non-photosynthetic and photosynthetic gorgonians; giant feather duster worms; sponges; and various macroalgae—all packed together in a glorious riot of color.And the fish! Captured in this image alone are schools (that’s right, schools!) of anthias, blue-green chromis, regal tangs, yellow tangs, and ocellaris clownfish. If you scan the image carefully enough, you might just spot royal and magenta dottybacks, a few royal grammas, various dwarf angelfishes, and maybe even Waldo peeking out from little niches. So, what could be wrong with such a magnificent image? Sounds like the sort of tank we’d all be proud to possess, right? Well, not so much. In addition to “magnificent,” this (clearly doctored) ad image, while definitely eye-catching, brings another word to mind: “misleading.” What’s more, I worry that these types of images might just inspire hobby newcomers to take the wrong approach right off the starting block

Squid Egg Masses

image credit:

image credit:

 There are around 500 different species of squid in our oceans, from the 1-inch-long sepiolid squid, to the enormous colossal squid, which can grow up to 45 feet in length – that’s about as long as a school bus!  Scientists are learning more and more about these interesting creatures, but, because many squid live far beneath the ocean’s surface, they are hard to observe, and we still have a lot to find out. One of the most interesting species is the Ommastrephid squid. These creatures can be as small as 10 cm and as long as 100cm, and are often the dominant squid in their habitat.  They are some of the strongest swimmers in the ocean, and are sometimes referred to as “flying squid”, because they glide along the surface of the water. These squid only live for about one year, and as soon as they reproduce, they die. Males mature first, and transfer their spermatophores on the still immature females. Then the females mature and spawn 300 to 4,000 small, elliptical or semi-spherical eggs. The squid migrate together, and lay all their eggs in the same area where they were born. The eggs hatch into larvae after only 5 days, depending on the water temperature The video below gives a fascinating peek into the flying squid’s reproduction – specifically, how the female makes her enormous egg masses.  Enjoy!
More: is the world's leading destination for sustainable coral reef farming and the aquarium hobby. We offer a free open forum and reef related news and data to better educate aquarists and further our goals of sustainable reef management.