Why should a tumor look like a crab?

Why should a tumor look like a crab?

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Origin of the word "cancer"

The disease was first called cancer by Greek physician Hippocrates (460-370 BC). He is considered the “Father of Medicine”. Hippocrates used the terms carcinos and carcinoma to describe non-ulcer forming and ulcer-forming tumors. In Greek this means a crab. The description was names after the crab because the finger-like spreading projections from a cancer called to mind the shape of a crab. - source

So the cancer cells spread in a way that tumor looks like a crab. Why? Why doesn't it, for example, have a potato-like spread in which cancer cells form a sphere?

Such projections are more formally known as spiculations. Most commonly, we talk about spiculations with respect to the radiographic appearance of malignant breast and lung lesions. This paper* describes the correlation between the mammorgraphic appearance of spiculated breast lesions and their pathology (microscopic appearance), which is a reasonable start at addressing the "why" question you pose. The authors define spiculations as follows:

A spiculated breast lesion is defined as a mass or an architectural distortion characterized by thin lines radiating from its margins.

Here is a picture taken from that paper which shows the mammographic appearance on the left and the microscopic appearance on the right, with the arrows pointing to the spiculations.

The linked paper gives many other examples of the microscopic and radiographic analysis of such tumors. It also explains that the two primary reasons for the spiculated shape are:

  • desmoplastic response
  • tumor infiltration (which occurs along anatomic ductal structures)

According to this report, the first explanation is more common. To understand the why behind the shape, we need to know the mechanism of this desmoplastic response. As described in the linked Wikipedia article, desmoplasia is not actually the tumor itself but dense fibrous tissue that is induced with malignant tumors invade healthy tissue. The mechanism of this is not entirely clear, but the Wikipedia article sets forth two theories:

  • The reactive stroma hypothesis postulates that tumor cells cause the proliferation of fibroblasts and subsequent secretion of collagen that acts as a scaffold. This scaffold apparently forms the outline of the "crablegs".
  • The tumor-induced stromal change hypothesis states that tumor cells themselves differentiate into fibroblasts and secrete the collagen that forms the spiculated scaffold.

*Franquet T, De Miguel C, Cozcolluela R, Donoso L. Radiographics. Spiculated lesions of the breast: mammographic-pathologic correlation. 1993 Jul;13(4):841-52.

"Cancer" is so named because the cancers Hippocrates first observed looked like crabs to him. If he had first observed cancers that most resembled potatoes, cancer probably would have been named differently today.

Cancerous growths reminded Hippocrates of a moving crab, which led to the terms carcinoma (malignant tumor) and cancer (ulcerated malignant tumor).


My point is, there is no "need" for a tumor to look like a crab or any other particular shape. Most tumors are probably irregular in shape. Most often they just look like lumps. I think breast cancer turns out to look like a crab fairly often (not sure why) and it was precisely breast cancer that Hippocrates was studying, probably because it's fairly close to the surface of the body, and, hence, fairly accessible and easy to observe. That's not irrelevant when there are no proper surgical techniques and anaesthetics.

Cancer is a homebody and has a primal need for security on the home front. But the Crab is also ambitious, like other cardinal signs, and is often tenacious when moving toward its goal.

Cancer's are Moon-ruled and can become a bit looney, especially when worn down, emotionally hurt, lonely or overwhelmed. Moods come and go quickly, and the Cancerian is intimate with the waxing and waning -- the Moon in all her phases.

This is the Zodiac sign of the Mother, originating waters, cozy closeness, emotional bonding (or bondage!) Cancer's depth of feeling is palpable, and its impulse is toward emotionally familiar people and places. Cancer is the keeper of the hearth and home, but they're eager to make a mark, too. They move indirectly, sensing the undercurrents, and developing strong ties of loyalty among friends and co-workers.

Cancer is at its most powerful when using the power of emotion to move people and experience meaning.

Oldest descriptions of cancer

Human beings and other animals have had cancer throughout recorded history. So it’s no surprise that from the dawn of history people have written about cancer. Some of the earliest evidence of cancer is found among fossilized bone tumors, human mummies in ancient Egypt, and ancient manuscripts. Growths suggestive of the bone cancer called osteosarcoma have been seen in mummies. Bony skull destruction as seen in cancer of the head and neck has been found, too.

Our oldest description of cancer (although the word cancer was not used) was discovered in Egypt and dates back to about 3000 BC. It’s called the Edwin Smith Papyrus and is a copy of part of an ancient Egyptian textbook on trauma surgery. It describes 8 cases of tumors or ulcers of the breast that were removed by cauterization with a tool called the fire drill. The writing says about the disease, “There is no treatment.”

Coconut Crabs (Birgus latro)

These are the biggest land dwelling crabs. They can weigh up to 4 kg (9.0 lb) and are about the size of a cat. They will eat almost any kind of food they come across, from fruit to dead animals. They are even capable of opening and eating a coconut, hence their name.

Coconut crab showing formidable claws

A freshwater crab, Potamon fluviatile, from Southern Europe

There are many species that live in fresh water--especially in the streams and billabongs of Australia--but also on every other continent.

The Southern European crab, Potamon fluviatile, pictured, has been eaten by people since Roman times.

Unfortunately, freshwater crabs are threatened by human activities more than most groups of animals and many species are in danger of becoming extinct.

Hermit crabs can be found in many habitats, on land, on shorelines and in deeper waters.

The back half of a hermit crab is soft and very vulnerable to predators. This does not matter because hermit crabs are clever enough to use a tough ready-made shell to protect the softer parts.

Usually, they find an unoccupied sea snail shell of the right size and simply reverse into it. When they grow too big they find another shell.

  • it saves them the energy of growing a complete exoskeleton for themselves
  • a sea snail shell is very tough and the hermit crab can withdraw completely into its protection if they are threatened.

This hermit crab looks like it needs to find a new shell.

Some Beautiful Crabs from Around the World

I will be adding pictures below of the most colorful, unusual or memorable carbs that I come across.

Sally Lightfoot Crab from South America

Charles Darwin probably came across the Sally Lightfoot Crab on his voyage in the Beagle. It is common on the Galapagos Islands, off the coast of South America.

Another kind of ghost crab (Ocypode species), this is the African variety.

Distribution and variety

Most crabs live in the sea even the land crabs, which are abundant in tropical countries, usually visit the sea occasionally and pass through their early stages in it. The river crab of southern Europe (the Lenten crab, Potamon fluviatile) is an example of the freshwater crabs abundant in most of the warmer regions of the world. As a rule, crabs breathe by gills, which are lodged in a pair of cavities beneath the sides of the carapace, but in the true land crabs the cavities become enlarged and modified so as to act as lungs for breathing air.

Walking or crawling is the usual mode of locomotion, and the familiar sidelong gait in the common shore crab is characteristic of most members of the group. The crabs of the family Portunidae, as well as some others, swim with great dexterity by means of their flattened paddle-shaped legs.

Like many other crustaceans, crabs are often omnivorous and act as scavengers, but many are predatory and some are vegetarian.

Though no crab is truly parasitic, some live commensally with other animals. One example is the little pea crab (Pinnotheridae), which lives within the shells of mussels and a variety of other mollusks, worm-tubes, and echinoderms and shares its hosts’ food another example is the coral-gall crab (Hapalocarcinidae), which irritates the growing tips of certain corals so that they grow to enclose the female in a stony prison. Many of the sluggish spider crabs (Majidae) cover their shells with growing seaweeds, zoophytes, and sponges, which afford them a very effective disguise.

The giant crab of Japan (Macrocheira kaempferi) and the Tasmanian crab (Pseudocarcinus gigas) are two of the largest known crustaceans. The former may span nearly 4 metres (12 feet) from tip to tip of its outstretched legs. The Tasmanian crab, which may weigh well over 9 kg (20 pounds), has much shorter, stouter claws the major one may be 43 cm (17 inches) long the body, or carapace, of a very large specimen may measure 46 cm (18 inches) across. At the other extreme are tiny crabs measuring in adulthood scarcely more than a centimetre or two in length.

Better-known anomuran crabs are the hermit crabs, which live in empty shells discarded by gastropod mollusks. As the crab grows, it must find a larger shell to occupy. If the supply of empty shells of appropriate size is limited, competition for shells among hermit crabs can be severe. In tropical countries hermit crabs of the family Coenobitidae live on land, often at considerable distances from the sea, to which they must return to release their larvae. The large robber, or coconut, crab (another anomuran) of the Indo-Pacific islands ( Birgus latro) has given up the habit of carrying a portable dwelling, and the upper surface of its abdomen has become covered by shelly plates.

As in most crustaceans, the young of nearly all crabs, when newly hatched from eggs, are very different from the parents. The larval stage, known as the zoea, is a minute transparent organism with a legless, rounded body, that swims and feeds in the plankton. After casting off its skin several times, the enlarging crab passes into a stage known as the megalopa, in which the body and limbs are more crablike, but the abdomen is large and not folded up under the thorax. After a further molt the animal assumes a form very similar to that of the adult. There are a few crabs, especially those living in fresh water, that do not pass through a series of free-living larval stages but instead leave the eggshell as miniature adults.

Alaska Snow Crab

U.S. wild-caught Alaska snow crab is a smart seafood choice because it is sustainably managed and responsibly harvested under U.S. regulations.


Above target population level.

Fishing Rate

Habitat Impacts

Habitat impacts from crab pots are minor because fishing occurs in areas of soft sediment such as silt and mud that are unlikely to be damaged by fishing gear.


Regulations are in place to minimize bycatch.

Population Status

  • According to the 2019 stock assessment, Alaska snow crabs are not overfished, and are not subject to overfishing based on 2019 catch data. Summary stock assessment information can be found on Stock SMART.


  • Alaska snow crabs have a hard rounded shell, four pairs of walking legs, and one pair of claws.
  • On top they are brownish in color and underneath they are lighter. Their eyes are green or greenish blue.
  • Males and females can be distinguished by the shape of their abdominal flaps. On males this flap is triangular, and on females it is broadly rounded.


  • Male Alaska snow crab can reach 6 inches in shell width but females seldom grow larger than 3 inches.
  • Scientists estimate that snow crabs may live for up to 20 years.
  • Females can carry up to nearly 100,000 eggs, depending on their size. They hatch their larvae in the spring when there is plenty of food in the water column.
  • When the eggs hatch, the larvae look like tiny shrimp.
  • The larvae feed on phytoplankton and zooplankton before metamorphosing into tiny crabs and settling on the ocean bottom.
  • Alaska snow crabs can only grow by molting (shedding their old shell and growing another).
  • After molting snow crabs are soft and vulnerable to predators until their new shell hardens.
  • When they have reached sexual maturity, both females and males undergo a “terminal molt,” after which they never molt again.
  • Snow crabs will eat almost anything they can catch and break open with their claws, including fish, shrimp, crabs, worms, clams, brittle stars, snails, algae, and sponges. They will also scavenge on anything dead they find.
  • Seals, sea otters, octopi, other crabs, and a wide variety of fish prey on Alaska snow crabs.

Where They Live

Fishery Management

    , the North Pacific Fishery Management Council, and the Alaska Department of Fish and Game manage the Alaska snow crab fishery.
  • Managed under the Fishery Management Plan for Bering Sea/Aleutian Islands King and Tanner Crabs, which defers management of crab fisheries to the State of Alaska with federal oversight. State regulations must comply with the fishery management plan, the national standards of the Magnuson-Stevens Act, and other applicable federal laws:
    • The Alaska snow crab fishery is currently managed according to the “three S’s” – size, sex, and season. Only male crabs of a certain size may be harvested, and fishing is not allowed during mating and molting periods. These measures help ensure that crabs are able to reproduce and replace the ones that are harvested.
    • Every year, managers set the harvest limit for the next fishing season using the most recent estimates of crab abundance.
    • Managers allocate shares of the harvest among harvesters, processors, and coastal communities through the crab rationalization program, which was implemented in 2005 to address economic, safety, and environmental issues in the fishery. This program includes a community development quota, which protects community interests by allowing community groups 10 percent of the harvest. They’re given the opportunity to purchase shares in the fishery before the shares are offered for sale outside the community.
    • Vessels carry vessel monitoring systems (satellite communications systems used to monitor fishing activities) and must report their landings electronically.
    • Fishermen must install escape panels and rings on their pots to prevent ghost fishing (when lost pots continue to capture and kill species) and to reduce bycatch.
    • Managers monitor catch in real time and are able to close the fishery when the harvest limit is reached.

    Observers are required on 20 percent of the vessels in the fishery. They collect data on catch and bycatch and document any violations of fishing regulations.

    Cancer the Crab

    The Sun awakened Cancer the Crab, a feminine sign in the zodiac on your birthday. The Sun in astrology stands for your inner nature, your essential character. The fourth sign of the Zodiac, Cancer is ruled by the restless Moon.

    A cardinal (creative and original) sign, Cancer governs home life, matters to do with women (especially the mother), as well as sensitivity and emotional intensity. It is a water sign, so Cancerian people are emotionally intense and deeper than they appear on the surface, while quite sensitive and understanding once you get through that tough exterior.

    Cancer Compatibility Click this to test your compatibility with all signs, or check out these signs, the most compatible for relationships with Cancer!
    Just click on the "glyph" or symbol to read the secrets of the signs.

    the Scorpion
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    The Sun, ruler of our inner nature, is somewhat dimmed in Cancer, the home of the Moon. Creative and romantic, with a strong love of home, family and tradition, you are a good communicator and a strong provider. Your deep sensitivity presents you with valuable and illuminating intuitions, especially regarding those you care for.

    Powerful Intuition

    Paradoxically combining a love of travel with a deep need for security, you surround yourself with sentimental objects from the past, including souvenirs, hand-me-downs and keepsakes. Cancerians are remarkably good at accumulating things indeed, you can be unwilling to throw anything out, even relationships that have passed their use-by date.

    Cancer is also good with money and generally takes a long-term view. The main thing to remember is not to let the powerful, turbulent emotions of the moment crowd out your normally rational judgement. Your intuitions are reliable and should be trusted you may even have natural psychic powers, which may be developed, given the right circumstances.

    Hard Shell

    The emblem for Cancer is the Crab, a creature with a very hard shell which protects a soft interior. The crab walks sideways, which is how the Cancerian skirts around a problem until forced to take it on with gritty determination and a creative flair. The crab's large claws hang on to its possessions for dear life, just as the Cancerian collects things to beautify the environment and bravely defends the home turf.

    Cancerians make good business people, combining artistry, originality and drive with an understanding of financial matters, marketing and the needs of the public. You can trust your intuitions, but you do need to generate a faith in yourself which will not be dampened by gloom or depression over what, in retrospect, may appear to be relatively insignificant problems. You have the natural ability to be diplomatic and to speak out when necessary or keep your mouth shut. Home and family ties will be significant in your life and developing a secure, comfortable home environment will be a boon to your state of mind, irrespective of your marital state.

    Emotional Release

    Physical fitness or sports activities can become important ways for you to work out emotional stress. Team sports are fun, for you can adopt team members as part of an extended family. Swimming, fishing, sailing and other water activities attract you, along with skiing, ice skating, and mountain climbing.

    Cancerians are creative. Even those among you who may not have any particular talent can use some involvement with art, music, or writing as another method of emotional release, rather than indulging in eating binges or other destructive habits. Living or spending time near the water is a relaxing, as well as creatively stimulating environment for Cancerians.

    Cancer rules the stomach, diaphragm, upper liver and breasts. People with Cancer active in their charts are subject to coughs, indigestion, gas, gallstones, general problems with stomach, liver and intestines, plus emotional disorders such as depression, hypochondria and hysteria.

    Ideal colours for the Crab are white, silver, and pale yellow. Cancer rules metallic silver, while both the ruby and the pearl are the traditional Cancerian birthstones. Silver reflects its environment in its shiny polished surface, yet it can tarnish and become dull unless properly cared for. In the same way, your sensitive nature reflects the people and circumstances surrounding you. The precious ruby, a variety of corundum, is one of the hardest minerals known, while the pearl is soft and easily scratched. Here we have the two contrasting sides of the Cancerian personality: hard and determined, yet simultaneously soft and vulnerable. Cancerian flowers are the water lily (lotus), iris, white poppy, white carnation and southern magnolia.

    Cancer cells can lose the molecules on their surface that keep normal cells in the right place. So they can break away from their neighbours.

    This helps to explain how cancer cells can spread to other parts of the body.

    What is triple-negative breast cancer?

    Cell receptors are special proteins found inside and on the surface of cells. These receptor proteins are the “eyes” and “ears” of the cells, receiving messages from substances in the bloodstream and then telling the cells what to do.

    Hormone receptors inside and on the surface of healthy breast cells receive messages from the hormones estrogen and progesterone. The hormones attach to the receptors and provide instructions that help the cells continue to grow and function well. Most, but not all, breast cancer cells also have these hormone receptors. Roughly two of three breast cancers test positive for one or both of these hormone receptors. (For a more complete explanation, see the Hormone Receptor Status page.)

    A smaller percentage of breast cancers — about 20% — make too much of the HER2 protein. In normal, healthy breast cells, the HER2 stimulates cell growth. When breast cancer cells have too much of the HER2 protein, however, the cells grow and divide too quickly. (For a more complete explanation, see the HER2 Status page.)

    Hormonal therapies and HER2-targeted therapies disrupt the effects of estrogen, progesterone, and the HER2 protein on breast cancer, which can help slow or even stop the growth of breast cancer cells.

    About 10-20% of breast cancers test negative for both hormone receptors and excess HER2 in the lab, which means they are triple-negative. Since hormones aren’t fueling the cancer’s growth, the cancer is unlikely to respond to hormonal therapy medicines, including tamoxifen and aromatase inhibitors. Triple-negative breast cancer also is unlikely to respond to medicines that target the HER2 protein, such as Enhertu (chemical name: fam-trastuzumab-deruxtecan-nxki), Herceptin (chemical name: trastuzumab), Kadcyla (chemical name: T-DMA or ado-trastuzumab emtansine), Nerlynx (chemical name: neratinib), Perjeta (chemical name: pertuzumab), or Tykerb (chemical name: lapatinib).

    Three common features of triple-negative breast cancer

    • Triple-negative breast cancer is considered to be more aggressive and have a poorer prognosis than other types of breast cancer, mainly because there are fewer targeted medicines that treat triple-negative breast cancer. Studies have shown that triple-negative breast cancer is more likely to spread beyond the breast and more likely to recur (come back) after treatment.
    • It tends to be higher grade than other types of breast cancer. The higher the grade, the less the cancer cells resemble normal, healthy breast cells in their appearance and growth patterns. On a scale of 1 to 3, triple-negative breast cancer often is grade 3.
    • It usually is a cell type called “basal-like.” “Basal-like” means that the cells resemble the basal cells that line the breast ducts. Basal-like cancers tend to be more aggressive, higher grade cancers — just like triple-negative breast cancers. Most but not all basal-like breast cancers are triple negative, and most but not all triple-negative breast cancers are basal-like.

    Who gets triple-negative breast cancer?

    Anyone can be diagnosed with triple-negative breast cancer. Still, researchers have found that it is more common in:

    • Younger people. Triple-negative breast cancer is more likely to be diagnosed in people younger than age 50. Other types of breast cancer are more commonly diagnosed in people age 60 or older.
    • Black and Hispanic women. Triple-negative breast cancer is more likely to be diagnosed in Black women and Hispanic women. Asian women and non-Hispanic white women are less likely to be diagnosed with this type of cancer.
    • People with a BRCA1 mutation. About 70% of breast cancers diagnosed in people with an inherited BRCA mutation, particularly BRCA1, are triple-negative.

    If you are diagnosed with triple-negative breast cancer

    It can be upsetting and scary to find out that you’ve been diagnosed with a type of breast cancer that is often more aggressive than other types and isn’t a good candidate for treatments that target the hormone receptors or HER2 protein.

    Still, it’s important to remember that the lack of hormone receptors and excess HER2 protein are just two factors that you and your doctor will take into consideration when deciding on a treatment plan. The stage and grade of the cancer are also crucial to your prognosis.

    It’s also important to remember there are therapies available that can treat triple-negative breast cancer.

    Results and Significance

    Mortality and wound size

    Crabs that did not suffer claw removal showed the fewest deaths. Wound size was an important factor in mortality and if the claw removal left a wound larger than 7 mm the crabs did not survive. The large wounds were more likely to come from unclean breaks where the removal was forced

    Feeding habits

    Crabs with no claws did not eat oysters or mussels, only fish. Crabs with a remaining pincer crab sometimes used other legs to stabilize mussels or oysters and crushed them with the pincer claw. In the wild if clawless crabs did not find readily available food that did not need to be crushed they may end up hungry.

    Influence of wound width on survival probability for stone crabs in laboratory. The graduated circles depict survival (0.0) and mortality (1.0), with the circle size proportional to the number of stone crabs represented (1−10).

    Measure of each prey type consumed for control stone crabs and stone crabs with one claw removed.

    Watch the video: What Cancer Looks Like! See What Cancer Looks Like On An Ultrasound (December 2022).