I want to know what a crustacean is, Yahoo Answers

i want to know what a crustacean is?

pleasee answer as soon as possible(:

6 Answers

They include various familiar animals, such as crabs, lobsters,

crayfish, shrimp, krill and barnacles. The majority of them are

aquatic, living in either marine or fresh water environments, but

a few groups have adapted to life on land, such as terrestrial crabs,

terrestrial hermit crabs and woodlice

Crustaceans (Crustacea) are a very large group of arthropods,

comprising almost 52,000 described species, and are usually

treated as a subphylum.

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A crustacean is an arthropod which is characterized by having two body segments (a cephalothorax and an abdomen), two pairs of antennae (preoral and postoral), and three pairs of feeding appendages.

Subphylum Crustacea includes such things as water fleas (daphnia), barnacles, isopods (such as woodlice), amphipods, decapods (including shrimp, crabs, crayfish, and lobsters), mantis shrimp, and krill among other less well-known animals.


What Are the Cockroaches of the Sea?

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«Cockroaches of the sea» is an expression of unknown origin that traditionally refers to lobsters. The bottom-feeding crustaceans, generally the blue American lobsters, have long been a staple in the North American diet, possessing a nutritious and rich flavor without the extra calories. Lobsters weren’t always the exquisite delicacy of five-star restaurants, though, and were once as common as cockroaches. Nowadays, «cockroaches of the sea» has come to represent a variety of creatures from the ocean.

Phylum (Arthropoda)

Cockroaches and lobsters belong to the same phylum: Arthropoda. Arthropods are invertebrates with exoskeletons, segmented bodies and jointed appendages. Most arthropods lay eggs and experience some form of metamorphosis. Phylum Arthropoda contains more species than all of the other phyla combined. Lobsters may look like cockroaches and crabs may look like spiders, but appearances are deceiving.

History of the Lobster

In the late 19th century, lobsters began to turn their bad image around. Native Americans used to use these sea bugs as bait and fertilizer, as well as nourishment. In the 1600s, lobsters were an easy catch as they washed up on shore and became the obvious source of protein for the poor. As lobsters piled up, prices dropped and prisoners, servants and slaves begged for different fare. June 15 is national lobster day, proving how far the bug has come. Native Americans wrapped lobsters in seaweed and cooked them over hot coals. Now the crustacean is chopped into special sauces and smeared onto hot dog rolls for $12 a pop.

Defining «Cockroach»

Many words have become synonymous with the cockroach: pest, nuisance, invasive, dirty, rampant. Cockroaches are the plague of hot climates, appearing under beds, behind walls and in drains, and they are rarely a welcome sight. In the past, lobsters were defined as scavengers, like cockroaches, of garbage and dead animal remains. Lobsters live on the ocean floor, eating a variety of fresh seafood, including crabs, clams and mussels. Cockroaches and lobsters do share the cannibal gene when times are scarce.

Other Cockroaches of the Sea

Shrimp, prawns, whales — even jellyfish earn the title of sea cockroach when they respond to ecological change by accelerating the reproduction process. Japanese fisheries claimed that minke whales were cockroaches for the very reason that there were too many, justifying a need to hunt and profit. Prawns, shrimp and lobsters all resemble bugs crawling across the floor of their ocean home.


A sea cockroach is any crustacean creature

In recent years, there’s been efforts from groups like the United Nations to get people eating insects — that is, to get those parts of the world that aren’t already eating insects, to start. The biggest argument in favor of bug-burgers is sustainability; bugs can be grown with an efficiency matched only by certain food crops, like corn, and provide a source of protein with few of the environmental or ethical drawbacks of meat.

Many people were revolted by this suggestion, even if they imagined a perfectly abstract ground-up-bug protein bar — but would these dainty citizens from the “front of the train” be so scandalized by an expensive lobster dinner? It’s certainly not sustainable, but new research suggests that there are at least some buggy species we Westerners find delicious, and they come exclusively from the sea.

This idea is actually the culmination of years of detailed genetic research, researchers reading and annotating various animal genomes to try to problem-solve their way back through evolutionary history. For a long time, it was thought that crustaceans and conventional insects had diverged a long time ago, and that similar body features like antennae were instances of species separately evolving along the same lines. This new, updated version of the tree of life tells a different story, and pegs modern insects as closer relatives to sea creatures like lobsters, crabs, and shrimp than centipedes and millipedes.

This simplified evolutionary tree shows the updated place for crustaceans.

This idea, that centipedes and millipedes were the last major evolutionary branding point from insects, has informed the search for a so-called ancestral insect, the first species after the final evolutionary split into what we today think of as insects. Working off of dogma, paleontologists have been looking for a primitive form that could have led to both mosquitoes and millipedes, when perhaps they should have been looking out for one sharing traits with delicious, buttery crab. Of course, this isn’t a totally new idea, and there are paleontologists who have spent years looking for just that sort of lobstery-sliverfish — no luck just yet.

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It makes sense that at least a few species of insect would make their way back into the water, over the course of evolution. There are all kinds of bugs that live on or in the water, especially for portions of their lives, and with such an abundance of space some individuals were bound to find that they could live and reproduce more efficiently while there. This is much like the choice by certain land-based mammals to start swimming further and further from shore, eventually becoming modern day whales and dolphins.

These guys have less in common with insects than we’d thought.

So, does this make you more likely to eat insects, less likely to eat lobster, or neither? Does it, conversely, impact your feelings about popping a live lobster or crab into a pot of boiling water?

The thick slabs of meat you get off a good-sized lobster are a little hard to conceptualize as insect meat, I’ll grant you, but according to the most modern data it really is accurate to think of lobsters as ocean-bound beetles. It does go to show the simple fact that insect meat need not necessarily be a total deal-breaker, in qualitative terms; with the right life-cycle, it would be possible to create a credibly food-bearing insect species. A creature with the lifecycle of a lobster could never address world hunger or agricultural inefficiency, but it could grease the wheels and be a first attack on people’s intrinsic hatred of eating insects.


Metallica Is Honored To Have A Crustacean Named After It

Metallica Is Honored To Have A Crustacean Named After It

Scientists discovered a colorless, eyeless creature which dwells in metallic environments deep in the northern Pacific Ocean. Naturally, they named it after the band Metallica.


Good morning. I’m David Greene. Deep in the Pacific Ocean lies a thing that should not be.


METALLICA: (Singing) He watches, lurking beneath the sea.

GREENE: Scientists discovered this colorless, eyeless creature — kind of like a worm. It dwells in metallic environments, and naturally, they named it after the band Metallica, which responded in a statement that it was an honor — quote, «We’ve made it into the Rock & Roll Hall of Fame, and now we’re a crustacean.»


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A sea cockroach is any crustacean creature


© 2002 Jonathan Bird
For Educational Purposes only

The largest phylum of creatures on Earth without a doubt is Arthropoda , both in terms of number of species and in total number of individuals. There are nearly 1 million species of Arthropods, with over 90% of them being insects. Of the remaining less than 10%, or about 85,000 species, there are only three major marine groups. The most well known is that of the mostly marine sub-phylum Crustacea (>30,000 species), the entirely marine class Pycnogonida , also called the «sea spiders» (500 species) and the entirely marine class Merostomata , commonly called the horseshoe crabs (5 species).

All Arthropods share certain characteristics making them unique from other phyla. Most obvious is the external skeleton (technically, not really a shell). Not only does this exoskeleton protect the animal like a suit of armor, but it actually does serve as the animal’s skeleton. The muscles of an Arthropod are connected to the inside of the exoskeleton, because the animal lacks an internal skeleton of any type.

The exoskeleton is made of a tough substance called chitin (KIE-tin). The animal secretes this hard material from cells in the underlying epidermis. Because the exoskeleton cannot grow, the animal must periodically shed its armor in order to grow. This process is called molting. The animal must first grow a soft exoskeleton underneath the principal exoskeleton. Then, the animal grows enough within the principal exoskeleton to crack it. The animal then crawls out of its old exoskeleton and allows the new soft one to grow and harden. New exoskeletons are usually too large for the animal at the time of the molt, and the animal must grow into the new exoskeleton. This allows reasonable time between molts. Immediately after an Arthropod has molted, it is quite vulnerable because it is essentially defenseless. During this period, the animal will hide and wait for its armor to harden. Lobsters caught during this period of time are sometimes called «soft-shelled» because they feel noticeably soft.

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The name Arthropod means «jointed-foot.» In order for the Arthropod to move in such a rigid body, it has numerous joints in its exoskeleton. Like door hinges, they allow bending in only one direction, but are surprisingly well developed. A lobster is quite flexible when necessary, and can manage to rotate its claws sufficiently to pinch its captor.

Arthropods have what is called an open circulatory system. This means that unlike many other kinds of animals, they have no arteries, veins or capillaries to carry blood. Instead, blood is pumped through sinuses (open spaces) within the animal to reach the tissues.

Arthropods also have compound eyes. Most people know of the insect’s compound eyes, and the other Arthropods’ eyes are no different. Each eye is composed of many smaller light-sensitive organs, called ommatidia. Together, these ommatidia form a single working eye. The compound eye is not specialized so much for detailed sight as for the detection of motion.

The Sub-Phylum Crustacea

The crustaceans are probably best known as a source of food. Lobster, crabs and shrimp are all Crustaceans. Barnacles, amphipods, isopods, and copepods are also Crustaceans.

Crustaceans have five pairs of appendages. Usually the front pair, called Chelipeds, have claws on them, while the remaining four pairs are walking legs. In many species, the second and even the third pairs of legs have smaller pincers on them as well.

While some of the primitive Crustaceans have a single body piece, called a trunk, the more advanced forms (like lobster, crabs and shrimp) have the body divided into two regions: a cephalothorax (or thorax) and an abdomen. The cephalothorax (meaning «head-body») is so called because it contains the «head» as well as the main body organs. The abdomen (which many people erroneously call the tail), on the other hand, is mostly muscular. The abdomen is usually made up of 6 segments, each containing a pair of «swimmerets» (small legs). In the male, the most forward pair of swimmerets are longer than the others, designed for inserting sperm into the female.

The last segment of the abdomen ends in a flattened section called the telson. The tailfan is composed of the telson and two flat appendages, called uropods, on each side.

Most Crustaceans are similar in appearance, with the most obvious exception of barnacles. The body form of the barnacle is Crustacean, but it isn’t very obvious unless examined at the larval stage. There are about 900 different species of barnacles known. Barnacles contain special glands which produce a type of «cement» which they use to glue themselves to rocks, ships, whales, docks and just about any other hard surface.

As barnacles grow, they create their own little «houses,» called carina, which look like tiny volcanoes. These are made of calcium carbonate which the barnacles make by combining carbon dioxide with calcium extracted from the water. When a barnacle is young, it is a planktonic larva with no protective carina and may become a meal for a larger animal. It must find a suitable place to settle and grow before it can start to produce a carina. Barnacles get their food by waving an arrangement of limbs called «cirri» in the water to catch drifting plankton. The cirri are present on even the larval barnacles—they are the legs. When the barnacle settles down to its adult form, it attaches itself to the substrate by the head and waves its legs to collect plankton.

The Class Merostomata

There are only five species contained within the Class Merostomata , and among those, only one is found in American waters. Commonly called the Horseshoe Crab ( Limulus polyphemus ), it is only found on the east coast of the United States, from the Gulf of Maine to the Gulf of Mexico. It is very common on Cape Cod. The animal is a tannish-brown color, but may accumulate algae growth, to look green in spots.

This creature (which, technically, is not really a crab at all, and is more closely related to the spiders and scorpions) has no relatives in the North Atlantic which look similar, and is therefore impossible to confuse with other Arthropods. Circa 1870, the horseshoe crab was given the name «horse-foot crab,» which is a better description of its shape than «horseshoe.» However, somehow the name became corrupted between then and now. It has a rounded («horse-foot shaped») carapace, with a triangular abdomen and a long, slender tail called a telson. On Sir Walter Raleigh’s expedition to the New World in 1584, naturalists Thomas Heriot and John White noted that the indians used the horseshoe crab’s tail (connected to a reed or stick) as a spear tip to spear fish.

The mouth is on the underside of the animal and is surrounded by five pairs of walking legs. Each leg is heavily armed with spines on the inside edge of the largest segment. These spines are called gnathobases and are used to grind up food (usually worms, clams and other small invertebrates) before it is eaten.

Watch the Emmy Award-winning educational underwater adventure program:

The Northern lobster, found in the northeast United States and Eastern Canada is a culinary favorite. It has large chelipeds more than capable of crushing the snails and clams on which it dines.

The Spiny lobster, such as this Caribbean species, has no large chelipeds. Instead, it uses long, spiny antennae as weapons. Anyone who has ever grabbed one of these lobsters without gloves has felt the effectiveness of these antennae!

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The Slipper lobster looks more like a giant underwater cockroach than a lobster. Its antennae have evolved into flat, shovel-like plates.

A female Rock crab, found in New England, holds her eggs under her abdomen. The orange ball of eggs contains thousands of baby crabs just waiting to hatch.

A Spotted Cleaner shrimp (Caribbean) hides among the venomous tentacles of an anemone, safe from predators. This shrimp uses its chelipeds to pluck parasites off fishes that come to the anemone for a cleaning. The shrimp gets a meal, and the fishes get cleaned.

An Acadian Hermit Crab in New England lives in a snail shell. When it grows too large for the shell, it has to find another one.

This extreme close up of a shrimp’s eye (smaller than a pin head) shows the ommatidia of the compound eye structure.

A barnacle is sort of like a shrimp standing on its head with its legs sticking out.

The Horsehsoe crab is an ancient animal that has proven incredibly important to medical research.

All images on these pages for non-profit educational use only.


‘Supergiant’ crustacean found in deepest ocean

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A huge crustacean has been found lurking 7km down in the waters off the coast of New Zealand.

The creature — called a supergiant — is a type of amphipod, which are normally around 2-3cm long.

But these beasts, discovered in the Kermadec Trench, were more than 10 times bigger: the largest found measured in at 34cm.

Alan Jamieson, from the University of Aberdeen’s Oceanlab, said: «It’s a bit like finding a foot-long cockroach.»

«I stopped and thought: ‘What on Earth was that?’ This amphipod was far bigger than I ever thought possible.»

It just goes to show that the more you look, the more you find Dr Ashley Rowden, Niwa

The strange animals were found using a large metal trap, which had been equipped with a camera, housed in sapphire glass to keep it safe from the high pressures of the deep sea.

Seven specimens were caught in the trap and nine were captured on film by the team from the University of Aberdeen, in Scotland, and the National Institute of Water and Atmospheric Research (Niwa), in New Zealand.

The largest specimen brought back up to the ship measured 28cm in length, while the biggest spotted on camera was 34cm-long.

‘Conspicuous animal’

Amphipods have been found living in large numbers at the very bottom of ocean trenches, deep, narrow valleys in the sea floor that can plunge down to nearly 11km.

The creatures are small, but extremely active, and seem to thrive in this place where the pressure is one thousand times greater than at sea level.

The name «supergiant» was first coined after large specimens were caught in the 1980s off the coast of Hawaii.

They have been seen since in the Antarctic, where they grew up to 10cm, but these are now dwarfed by this latest find.

Dr Ashley Rowden, from Niwa, said: «It just goes to show that the more you look, the more you find.

«For such a large and conspicuous animal to go unnoticed for so long is just testament to how little we know about life in New Zealand’s most deep and unique habitat.»

Over the last few years, scientists have been surprised by the life that is found in ocean trenches.

These deep-sea spots were once thought to be barren; too dark, cold and with too much pressure for anything to survive.

But researchers have found a wealth of life in the deepest of the deep.

As well as swarms of amphipods, they have uncovered shrimp-like creatures called isopods and snailfish that live 7,700m down.


Is This a Real ‘Sea Roach’?

A video purportedly showing a sea roach actually shows an animatronic sea mite from the movie «Pacific Rim.»

  • Published 22 April 2017


A video shows a real sea roach.



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A video of a strange, large insect-like creature occasionally appears on the Internet, along with the claim that it shows a creature bearing the evocative name “sea roach”:

Although there is a real animal nicknamed the sea roach, a marine woodlouse also called a “sea slater”, the creature pictured in this video is not one. This is actually a video of an animatronic creature that was created by the visual effects studio Spectral Motion for the 2013 movie Pacific Rim. Spectral Motion released a video showing the creation these parasitic creatures called “skinmites” which lived on the back of the Kaiju:

As for today, let’s look at a video detailing their animatronic Kaiju parasites used in Guillermo del Toro’s Pacific Rim. They are also referred to as Skinmites, and I guess, Rollie Pollies? Reminder for those that forgot, these are the creatures that live on the Kaiju, much like a Remora fish does with a shark.

Here’s a comparison of the “sea roach” and the Kaiju Skinmite:

One reason that this video may have fooled viewers is that the Kaiju Skinmite bears a passing resemblance to a real deep sea creature: The giant isopod. Another (real) image of a giant isopod was circulated earlier this year along with the claim that it showed a fictional creature called a Georgia Speekle.


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