28 Mar 2007

How Can I Tell My Cray's Gender?

Dear Blue Lobster:

I have two fresh water blue lobsters and I hope to breed them. I can't tell if there male or female. Can you help me determine their gender? How can you tell if they are male or female? Also, does it matter if one is about 1/8 of an inch smaller than the other?


Dear Gentle Sir:

Unfortunately, checking a cray's gender is not as easy as lifting its legs and peeking. It involves being able to classify your cray by species, molting phase, and health. It's no surprise that even most professionals can only guess at gender and typically use breeding pools instead of breeding pairs.

Knowing your cray's species is the first step: Do you have a Red Swamp Crayfish (Procambarus clarkii) or a Red Bayou Crayfish (Procambarus kentii)? Without first knowing the species, gender identification becomes difficult, if not impossible, as we shall see below.

A crayfish's phase is the next important thing to know. A phase is simply a morphological structure the cray adopts for mating. Their phase changes at molts and comes during breeding season. Crays exposed to videos of mating pairs have also molted into a breeding phase.

The structural differences are unique among genera and species. For instance, a male Red Jaconda Cray (Cancerita rojoƱa) during non-breeding Phase I resembles a female Clouded Cray (Cancerita nublado), a closely related species. As you can see, this gets complicated.

Overall health is one last factor. Obviously, a cray whose appendages have been chewed off completely will be difficult to sex, as will one which is too small to study closely. Also, not all cray species exhibit sexual dimorphism, so size isn't a good identifier unless you first discern the species.

One method of sexing crays scientists have had some success with has been taking cray whose gender is known, grinding it into a paste, and releasing the paste into a holding tank with other crays of the same species. The crays that respond first will be members of the opposite gender to the ground cray, as they respond to the pheremones in the offal.

Good luck identifying your cray's species, gender, and phase. If you're lucky you'll have a well-known species you can identify quickly and without much mess.

21 Mar 2007

Why Does My Cray Change Colors?

Dear Blue Lobster:

I have two electric blue lobsters and when I got them they were blue but now they seem to be brown with a little orange here and there. What would cause this: Could they be molting and how can I tell. How long does it take for them to molt?



Dear Gentle Sir:

Cray color can be influenced by a number of factors, including genetics, environment, breeding, and lighting.

If the cray is genetically blue, it will remain blue for its life, though its shade may vary. As noted in other columns, crays can be bred for different colors and patterns. One notable new color morph in Procambarus clarkii is called the "Ice Morph," where the cray is entirely white save for its eyes and resembles an albino or a cave species. It is rare and goes for hundreds of dollars.

Sometimes crays will change color slightly to match their environment. Again, the Procambarus clarkii is highly adaptable and can be naturally found with red, orange, brown, green, and gray color morphs, all to match their environments. A cray living in dense weeds will tend towards green while one living in a creek with heavy iron deposits will grow orange. You may find a cray that changes from light to dark or vice versa depending on your tank lighting and gravel shade.

During mating season, the cray will molt in anticipation of the coming intercourse and exhibit color changes. This is called the second, or mating, phase of the cray's color patterns. The Orconectes rusticus will change from a dull tan to a dark grey with vivid red, white, and black stripes on its claws. Cambarides coccus, the Peacock Cray, turns from a dark brown color to a motley of yellow, green, red, and blue spots before it sets out to find a mate. The next molt after mating season will put them back into their first color phase.

Lighting can do some spectacular things to your crayfish too. Using fluorescent lights that mimic natural sunlight, the cray is likely to take on stronger hue and vibrancy. Using old incandescent lights can result in more muted tones, and colored incandescence can alter the undertone of the cray. Using Day-Glo lights will result in crays that glow in the dark, giving off an eery psychedelic luminance. One species of cray even phosphoresces due to the deposits of the mineral in the water where it lives, which helps constitute its shell.

To answer your question directly, unless your cray is crawling out of its shell it's not actively molting but color changes can indeed happen directly after molts: The changes have been there all along underneath its old shell waiting to come out. Think of the cray's new colors as the real him opening up to the world saying, "This is just who I am!"

14 Mar 2007

The Highland Lobster, Homarus Hebridum

Dear Blue Lobster:

My family are Scotch-Irish and I am a huge crayfish fanatic. Since it's almost St. Patrick's Day, I was hoping you could tell me about the subspecies of the European Lobster that lives near northern Great Britain.

Brian MacGliomach

Dear Gentle Sir:

The lobsters of northern Britain are currently in taxonomic flux.

They differ from other populations of European lobsters by being somewhat larger and greener. It is thought that the cooler waters of the North Sea and North Channel have made the populations there hardier. There is debate as to whether they should be classified as a species (Homarus hebridum) or as a subspecies of the European lobster.

These lobsters also have incredibly long life-spans. One specimen captured was 2 meters long and weighed 80 kilograms and is thought to have been over 350 years old. Most European lobsters live about 50 years at most.

Behaviorally, the populations around northern Britain exhibit unique characteristics. During the mating season in the Spring, the males of each population gather at a certain point on the sea floor. No one yet understands how they know where to navigate to, as the location changes each year. There they fight one another until only one remain.

When the corpses are tallied and only one remains, the final lobster has such a powerful life force that it then proceeds to mate with all of the females in the region for days on end. At the end of this sexual spree it buggers off to live a peaceful life, dying alone but knowing that millions of its progeny will soon flood the water column as plankton.

Molecular research continues in hopes of one day decoding the secret of this population's unique characteristics.

8 Mar 2007

The New Caledonian Neoglyph

Dear Blue Lobster:

I read about some ancient lobster that was found near Australia. What can you tell me about it? Is it really a "living fossil?"


Dear Gentle Sir:

Discovered in the remote sea near New Caledonia, the creature you refer to — the New Caledonian Neoglyph — has captivated scientists and laymen alike.

Discovered in 2005 and described in a 2006 paper, the new species represents an extant type of crustacean thought to have gone extinct long ago. Indeed, it has many interesting behavioral and physiological characteristics that will make it important in understanding pleocymate taxonomy in years to come.

The term "living fossil," however, is a bit of a misnomer. It actually just means that a certain organism has changed very little over long spans of time. The scientific term for this is "archeomorph," which means "ancient form."

A sister species, the Fenix Lobster (Neoglyphea inopinata) was discovered early last century and together with the N. neocaledonia represent a group of crustacrans thought to have gone extinct some 50 million years ago in the Eocene. The glyphids have eyes suited for scouring the benthos, or deep-sea floor, and specially-modified chelicerae for picking through the cold detritus at the bottom of the ocean.

To the casual observer, the Neoglyph resemble a cross between a shrimp or prawn and a lobster, and indeed scientists believe it is an ancient lineage early in decapod evolution closely related to early lobsters or shrimp groups, possibly dating from almost 400 million years ago. Molecular testing will soon place the family taxonomically. It is thought to belong with Reptantia.

Several specimens of the New Caledonian Neoglyph are now on display at the National Zoo & Aquarium in Canberra, Australia. The zoo is attempting to initiate a breeding program for the creatures.

6 Mar 2007

Meet the Larsen Ice Shrimp

Dear Blue Lobster:

Is it true that someone named a shrimp after gary larson, the guy who drew the far side cartoon?

w. "pappy" brimley

Dear Gentle Sir:

While there is a shrimp called Larsen, it's not named for the cartoonist but instead an Antarctic habitat recently revealed to science.

After the Larsen B ice shelf collapsed in early 2002, scientists discovered a completely new ecosystem untouched for the last 12,000 years, along with a completely new decapod species. Called the Larsen Ice Shrimp until it can be classified, this crustacean has the uncanny ability to freeze and unfreeze itself within seconds in order to dodge predators and conserve energy during the hard winter months.

The Ice Shrimp uses its freezing abilities by means of alcohol, which it produces from foodstuffs in small quantities and circulates throughout its body. When it is threatened, it releases the alcohol through its anus, which causes its body to freeze solid. The alcohol free in the water also serves to disorient predators. When danger has passed, the shrimp releases a chemical that rapidly converts stored food into alcohol, defrosting it.

In the Winter season, from March through August, the Ice Shrimp enters two different metabolic states in order to conserve energy. In torpor, it remains viable but motionless, simply waiting for food to come along rather than scouting for it. If it has gone more than a month without food, it will bury itself in the substrate of the ocean floor and then freeze itself until September, when the Summer season begins and food becomes more abundant.

Scientists are now studying the Larsen Ice Shrimp in hopes of more effective treatments for hypothermia as well as one day being able to stockpile human organs for later transplantation.

3 Mar 2007

The Case of the Upside-Down Crabs

Dear Blue Lobster:

We have 12 tropical red crabs 6 of whom have in the last 24hrs taken to living UPSIDE DOWN. They twitch and stretch and my poor girlfriend is convinced that they are going to die. Please can you reassure her that they are fine and just looking for a different perspective on life?

Thanks for your help.


Dear Gentle Sir:

While crustaceans sometimes strive to see the world from a different point of view than they are accustomed to, crabs are more likely to just remain cantankerous or "crabby," as their name befits them. I will be both blunt and honest: Your crabs are either molting or dying.

In the case of the former, keep the water temperature and chemistry as they are now. If the other crabs seem aggressive toward them, introduce a tank divider to keep the molting crabs safe while they are soft, or as the crabbing industry calls them, "turds."

If the latter is the case and your crabs are expiring, by the time this response is published it may be too late and for that I am deeply sorry. I will include your crabs in my vigils.

If they yet live, check healthy crabs for odd behavior. If it's a tank chemistry problem, all of the crabs are likely to die at some point. If there are high levels of nitrids in the water or the pH is more than a few tenths of a point away from neutral, fix these problems immediately! Remove any pennies from your aquarium and turn your tank filter up to eleven.

I also point you to the case of the upside-down crayfish, a similar but ultimately tragic situation.