Creepy things Mike plays with
Wednesday, July 09 2008 | Comments (0)
A cave cricket.
In this week’s episode Mike explored a cave and found cave crickets and crayfish, then he went fishing for hag fish, also called slime eels. You may wonder what these critters are and, lucky you, you’re about to find out.
Cave Crickets
Cave crickets, nicknamed sprickets, because their legs resemble a spider’s, are part of the orthopteran family Rhaphidophoridae, which include: cave wetas, cave crickets, camel crickets and sand treaders. Most of these critters are found in caves, cellars and other similar places. They are found on every continent and many islands. Some even reach to the alpine areas and live close to permanent ice.
Cave crickets have vary large hind lets and long, slender antennae. They are a brownish color and wingless. The cricket’s body may grow up to two inches long. Young crickets appear almost translucent.
Their limbs and antennae help them navigate in the lightless bowels of a cave. They have also been known to eat their extremities, despite the inability to grow them back, in order to avoid starvation.
The crickets serve little economic importance, but as we learned in this week’s episode, they provide food for other cave dwelling organisms.
They usually do not reproduce indoors, unless provided with an environment similar to a cave, with food close by.
Due to their limited vision, the crickets also use their large hind legs to jump toward any threat in an attempt to scare it away. Although they may appear to be a dangerous version of the field cricket, these bugs are relatively harmless to humans.
So, fear not, Mike was completely safe – if he could only avoid sliding down hills on his butt.
Cave Crayfish
These little guys go by the name, Cambarus aculabrum. They are small, albino and cave-dwelling. The crayfish may reach an overall body length of about 3.75 inches.
They are specially adapted to dark surroundings, exhibiting such features as reduced eyes, lack of pigmentation, a reduced metabolic rate, delayed reproduction, and reduced egg production.
The crayfish feeds on organic matter carried in by cave streams or left by other animals such as bats, or cave crickets. Some scientists estimate the cricket can live as long as 75 years.
Surprisingly enough, given their location in a once contaminated cave, the crickets are extremely sensitive to the quality of the water in which they live. They are adapted to the clean, filtered water of underground streams and must have dissolved oxygen in the water for respiration.
Contamination of water by sewage, animal waste, petroleum products, or any number of chemicals can deplete oxygen concentrations and can suffocate them. Which was part of what proved to the biologists Mike spoke to that the cave was fairly clear of waste.
Since cave organisms have a low metabolic level and limited opportunities to feed, any disturbance uses up energy that could be used in feeding or reproduction. So, when spelunkers or cavers disturb them, it may be detrimental.
The crawfish have a low reproductive rate and a relatively long maturity period, so illegal collection of any cave crayfish will affect the ability of the species to reproduce. State governments protect many of these species.
In this week’s episode, the blind crawfish were a new discovery by the biologists Mike traveled with.
This particular kind of blind crayfish has never before been found west of the Mississippi River. The discovery brings to the number of cave crayfish species in North America to 39. Before this, there were only two known species of cave crayfish in Missouri.
The Hagfish Does it look like dinner to you?
Hagfish
Hagfish are marine craniates, meaning they contain vertebrates and Myxini, as living representatives, and have a skull. This means they are the only animal to have a skull, but not a vertebral column.
There is some dispute about whether they are strictly fish, but one thing is certain, they are not eels, despite the name “slime eel.”
They are usually about 18 inches long and have elongated, eel-like bodies with paddle-like tails. Their colors vary from species to species, but they range from pink to a bluish-grey. They have larger jaws than their non-cave counterparts and more teeth.
The eyes may be vestigial, meaning they have lost most of their function, or absent altogether. They have six barbels, whisker-like organs, around the mouth and a single nostril. The jaws have a pair of horizontally moving structures, rather than vertical.
They have a circulatory system that contain both open and closed blood vessels, with a primitive heart system, bearing some resemblance to a worm. They have four hearts as well, the brachial heart, which functions as the main pump and three accessory hearts – the portal heart, which carries blood from the intestines to the liver; the cardinal heart, which move blood from the head to the body and the caudal heart, which pump blood from the trunk and kidneys to the body.
Perhaps the best know characteristic, at least from this week’s episode, is the slime. They exude large quantities of slime, or mucus, from pores located all over their bodies. If captured they secrete the slime which allows them to escape. They then tie themselves into a knot that slides down the length of their body and scrapes the slime off. An adult fish can secrete enough slime to turn a large bucket of water into slime within minutes.
Very little is known about reproduction. If the species is dying out, however, they can switch between male and female. They have both testes and ovaries, but the female gonads remain non-functional until they reach a certain stage in the lifecycle. The females lay 20 to 30 eggs.
As we learned this week, they eat fish, living and dead. They feed on the insides, which is another reason for the slime – it protects them from the acids inside the fish.
In recent years, they have become a special interest to genetic analysists who are investigating the relationships among chordates.
Mike asked if their was a use for the slime and was told no, but recent studies showed that the mucus is unique and includes strong, threadlike fibers, similar to spider silk. Scientists say some possible uses include biodegradable polymers, space-filling gels or as a cauterizing agent. Or maybe the new fad will be a slime coat.
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