The Invertebrates Have Arrived in BPC's New Reef Aquarium

BPC Reef Tank - September 2016

As many of you know, BPC has a new aquarium in the first floor lobby of the Athena building. Erin Janoff, aquarist and owner of The Octopus's Garden, is facilitating its development into a vibrant reef tank! This is no ordinary fish tank. Wikipedia describes a reef aquarium as "a marine aquarium that prominently displays live corals and other marine invertebrates as well as fish that play a role in maintaining the tropical coral reef environment. A reef aquarium requires appropriately intense lighting, turbulent water movement, and more stable water chemistry than fish-only marine aquaria." Erin has spent the last few weeks assembling the machines and prepping the watery environment.

On September 12th, the first animal was added - a pioneering hermit crab. (You can watch the video of Mr. Nelligan adding this pioneering invertebrate by clicking the video below or accessing this link.)

Invertebrates awaiting their release

On Friday, September 16th, more invertebrates were added. Most of these invertebrates will help keep the tank clean. They are listed here along with their taxonomic classification. (See bottom of this post for the Tree of Life BPC 7th graders are currently using in their study of life sciences!) 

• a few Nassarius snails - These carnivorous snails are scavengers and are important members of the reef aquarium's cleanup crew. Nassarius is a genus under the phylum Mollusca and class Gastropoda, and there are many, many species in this taxon!  If you look carefully, you'll see them buried in the sand with just their proboscis ("nose") sticking up until it is feeding time.

• A Stomatella snail - These snails look more like slugs than regular snails, although they do have small flat shells.  They belong to the Stomatella genus in the phylum Mollusca and class Gastropoda, and there are around 20 different species. These snails are herbivores, and help keep the tank clean of algae. 

• A Trochus snail - Trochus is a genus under the phylum Mollusca and (you guessed it) class Gastropoda, and there are about 24 species in this genus. [UPDATE: We now have two in there, as a second Trochus snail hitchhiked on an incoming rock!]

• A number of crabs - these scavengers (all in the phylum Arthropoda) help keep the tank free of uneaten food and algae, especially of "nuisance algae" and cyanobacteria (also known as "red slime algae"!)
• Four Emerald Crabs (Mithraculus sculptus)  
• Two Red Legged Hermit Crabs (Clibanarius digueti)  
• Two Halloween Crabs (Ciliopagurus strigatus)  

• One Decorator crab - Decorator crabs are part of the superfamily Majoidea (although not all Majoidea are decorators).  Decorator crabs may belong to a number of different genera.  It looks like we have a Spider Decorator Crab (Camposcia retusa).  Decorator crabs stick materials from their environment on themselves for camouflage.

Sonam watches as the decorator crab is dropped into the tank.

• One Tiger Tail Sea Cucumber -This scavenger is an omnivore and in the phylum Echinodermata, most likely in the genus Holothuria.  Fun fact: these sea cucumbers have the potential to be poisonous if stressed, which shouldn't happen unless it gets sucked into a pump or something. [UPDATE 9.26.16: Erin suspects the sea cucumber has been eaten by the crabs and or the Nassarius snails! So, it is either buried in the sand or digested (also known as being "at one with the system"!)] 

• lots of other tiny invertebrates, like tiny worms, sea stars and shrimps got in there, too!

Last Tuesday, Erin added two living rocks, two powerheads (flow pumps), and lights to our tank.  The powerheads are held to the glass by powerful magnets. 

Erin adjusts the underwater fans.

The "living rocks" are full of algae and green zoanthids. Zoanthids are in the phylum Cnidaria. (There are at least seven families, 16 genera, and many, many species.) Zoanthids feed both by photosynthesis (helped by the zooxanthellae they have inside them) and by capturing plankton and floating matter.  (Another fun fact: zoanthids produce a substance called palytoxin, considered to be one of the most toxic non-protein substances known.) "Algae" is an informal term used to describe a large group of photosynthetic organisms which are not necessarily closely related. Erin added a bunch of macroalgae to our reef tank--the snails tend to eat the "2D algae" on the sides of the tank, while fish and crabs eat this "3D algae" on the rocks. And I have no doubt those rocks are also full of many microbes such as bacteria!

The powerheads provide a turbulent water environment for these sessile (or non-mobile) organisms.  Because some animals are attached to the rock, their food must come to them. They passively wait for food to pass by and touch their tentacles--then they discharge their nematocysts (basically tiny, poisonous harpoons) to capture their prey and draw it toward their mouths.  (Check out this cool video of sea jelly nematocyts firing!) The fans are also necessary to blow the animals' waste away from them. (Fun fact: these simple animals have one opening--food goes in and waste goes out of the same hole!)

The LED lights are on timers and give a rhythm to the reef creature's day.  Since many of the organisms are photosynthetic autotrophs, they need the light to make their own food.  And the creatures need the darkness to know when to sleep!

We've even started a little reef library in the lobby (pictured left), and some students made welcome paper flowers for the crabs (pictured right).













Stay tuned for even more tank news!

An example of the Tree of Life handout used in 7th grade!