''Toxopneustes pileolus'', commonly known as the flower urchin, is a widespread and commonly encountered
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of
sea urchin from the
Indo-West Pacific
The Indo-Pacific is a vast biogeographic region of Earth.
In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...
. It is considered highly dangerous, as it is capable of delivering extremely painful and medically significant stings when touched. It inhabits
coral reef
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups.
C ...
s,
seagrass
Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the or ...
beds, and rocky or sandy environments at depths of up to . It feeds on
algae,
bryozoans, and organic detritus.
Its common name is derived from its numerous and distinctively flower-like
pedicellaria
A pedicellaria (plural: pedicellariae) is a small wrench- or claw-shaped appendage with movable jaws, called valves, commonly found on echinoderms (phylum Echinodermata), particularly in sea stars (class Asteroidea) and sea urchins (class Echi ...
e, which are usually pinkish-white to yellowish-white in color with a central purple dot. It possesses short and blunt spines, though these are commonly hidden beneath the pedicellariae. The rigid "shell" (
test
Test(s), testing, or TEST may refer to:
* Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities
Arts and entertainment
* ''Test'' (2013 film), an American film
* ''Test'' (2014 film), ...
) is a variegated deep red and gray in color, though in rare cases it may be greenish to light purple.
Taxonomy
''Toxopneustes pileolus'' is one of four species belonging to the
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
''
Toxopneustes''. It belongs to the
family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
Toxopneustidae
Toxopneustidae is a family of globular sea urchins in the class Echinoidea.
Characteristics
All Camarodonts have imperforate tubercles and compound ambulacral plates. In addition, the Toxopneustids are characterised by the peristome, or open ...
in the
order Camarodonta. It was originally described as ''Echinus pileolus'' by the
French naturalist Jean-Baptiste Lamarck
Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck (1 August 1744 – 18 December 1829), often known simply as Lamarck (; ), was a French naturalist, biologist, academic, and soldier. He was an early proponent of the idea that biolo ...
in 1816, in the second book of his ''Histoire naturelle des animaux sans vertèbres'' series. It was later used as the
type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...
for the newly created genus ''Toxopneustes'' by the
Swiss American biologist
A biologist is a scientist who conducts research in biology. Biologists are interested in studying life on Earth, whether it is an individual Cell (biology), cell, a multicellular organism, or a Community (ecology), community of Biological inter ...
Louis Agassiz.
The generic name ''Toxopneustes'' literally means "poison breath", derived from
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
τοξικόν
άρμακον(''toksikón
hármakon', "arrow
oison) and πνευστος (''pneustos'', "breath"). The specific name ''pileolus'' means "little cap" or "skullcap", from
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
''
pileus'', a kind of brimless conical felt cap. In
English
English usually refers to:
* English language
* English people
English may also refer to:
Peoples, culture, and language
* ''English'', an adjective for something of, from, or related to England
** English national ide ...
, ''Toxopneustes pileolus'' is most widely known as the "flower urchin".
It is also sometimes known under various other common names, including "trumpet sea urchin",
"flower tip urchin",
"felt cap sea urchin",
and "poison claw sea urchin".
In the
seashell collecting trade, ''Toxopneustes pileolus'' is known as the "mushroom urchin", due to their spineless empty shells (
tests) resembling the caps of
mushrooms
A mushroom or toadstool is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denotes one poisonous to humans.
The standard for the name "mushroom" is ...
.
It is also known as ''tapumiti'' in
Samoan;
''tehe-tehe batu'' in
Sinama
The Sama language, ''Sinama'' (''Sama'' + the infix ''-in-''; also known as Bahasa Bajau), is the language of Sama-Bajau people of the Sulu Archipelago, Philippines; Sabah, Malaysia and parts of Indonesia. The Sama are one of the most widel ...
and
Tausug;
''rappa-uni'' (ラッパウニ) or ''dokugaze'' (毒ガゼ) in
Japanese
Japanese may refer to:
* Something from or related to Japan, an island country in East Asia
* Japanese language, spoken mainly in Japan
* Japanese people, the ethnic group that identifies with Japan through ancestry or culture
** Japanese diaspor ...
;
and ''lǎbā dú jí hǎi dǎn'' (喇叭毒棘海膽) in
Chinese
Chinese can refer to:
* Something related to China
* Chinese people, people of Chinese nationality, citizenship, and/or ethnicity
**''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation
** List of ethnic groups in China, people of ...
.
Description
Flower urchins are relatively large sea urchins. They can reach a maximum diameter of around .
Like most
echinoderm
An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the s ...
s, the body of adult flower urchins is equally divided into identical segments around a central axis in multiples of five (
pentaradial symmetry
Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, take the face of a human being which has a pla ...
). The rigid "shell" (
test
Test(s), testing, or TEST may refer to:
* Test (assessment), an educational assessment intended to measure the respondents' knowledge or other abilities
Arts and entertainment
* ''Test'' (2013 film), an American film
* ''Test'' (2014 film), ...
) has five
interambulacral segments separated from each other by five
ambulacral
Ambulacral is a term typically used in the context of anatomical parts of the phylum Echinodermata or class Asteroidea and Edrioasteroidea. Echinoderms can have ambulacral parts that include ossicles, plates, spines, and suckers. For example, sea ...
segments, each of them are composed of smaller regularly interlocking plates. It is overlaid by a thin layer of skin in living individuals. The test is variegated in coloration, usually deep red and grey, though there are rare instances of green and pale purple.
Each ambulacral segment is ornamented by a large purple zigzag pattern running along its length.
Two rows of
tube feet
Tube feet (technically podia) are small active tubular projections on the oral face of an echinoderm, whether the arms of a starfish, or the undersides of sea urchins, sand dollars and sea cucumbers; they are more discreet though present on br ...
emerge from the grooves on either side of each of the ambulacral segments (for a total of ten rows). The tube feet are individually composed of a thin muscular stalk (podia) tipped with a small suction cup (ampulla). The
mouth is centrally located in the bottom (oral) surface of the test. It is surrounded by a ring of small plates overlaid by softer tissue known as the
peristome Peristome (from the Greek ''peri'', meaning 'around' or 'about', and ''stoma'', 'mouth') is an anatomical feature that surrounds an opening to an organ or structure. Some plants, fungi, and shelled gastropods have peristomes.
In mosses
In mosse ...
. Embedded in the peristome are five
calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.
In zoology
''Calcareous'' is used as an ad ...
"teeth" collectively known as
Aristotle's lantern. These are used for grinding the flower urchin's food. The
anus is situated on the upper (aboral) surface of the test, directly opposite the mouth. Like the mouth, it is surrounded by a ring of small plates known as the
periproct The periproct is the final body segment in annelid worms. The anus is located on this segment. The term also refers to the small region surrounding the anus of the sea urchin.
See also
*Prostomium
*Earthworm
*Sea urchin
Sea urchins () are s ...
. Surrounding the anal opening are five smaller holes (the genital pores) which are directly connected to the
gonads inside the body cavity.
The most conspicuous feature of flower urchins are their
pedicellariae
A pedicellaria (plural: pedicellariae) is a small wrench- or claw-shaped appendage with movable jaws, called valves, commonly found on echinoderms (phylum Echinodermata), particularly in sea stars (class Asteroidea) and sea urchins (class Echinoi ...
(stalked grasping appendages). Flower urchins possess four types of pedicellariae, distinguished by form and function, but only two are abundant. The first type are the ophicephalous pedicellariae. They resemble tube feet, except they end in three small claws (called valves) rather than suction cups. These are used to keep the body surface clear of algae,
encrusting organisms, and unwanted debris.
The second type are the globiferous pedicellariae which superficially resemble flowers (hence its common name).
These are more specialized and are used for defense against
predator
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
s and larger
ectoparasites. Globiferous pedicellariae also end in a three-valved claw-like grasping appendage, like they do in ophicephalous pedicellariae, but they are much larger.
The valves are connected to each other by a distinctive circular membrane around in diameter. They are pinkish-white to yellowish-white in color with a central purple dot and a bright white rim.
Each valve ends in a sharp fang-like tip which is capable of penetrating human skin.
The base of the valves also house venom glands.
Some authors further subdivide globiferous pedicellariae into two subtypes based on size - the trumpet pedicellariae and the giant pedicellariae.
The other two types of pedicellariae - tridentate and triphyllous - are rare or restricted only to certain areas of the test.
The relatively blunt
spines are quite short and are usually hidden below the flower-like pedicellariae. They can vary from white, pink, yellow, light green, to purple in coloration with lighter-colored tips.
Other members of the genus ''Toxopneustes'' are similar in appearance and can be mistaken for flower urchins. ''
Toxopneustes roseus'' can be distinguished by the uniform coloration of their tests of pink, brown, or purple. It is also restricted to the
East Pacific and thus aren't found together with flower urchins. ''
Toxopneustes elegans'', which is only found around
Japan, can be distinguished by the presence of a distinctive dark stripe just below the tips of their spines. ''
Toxopneustes maculatus'' is a very rare species known only from specimens from
Réunion,
Christmas Island
Christmas Island, officially the Territory of Christmas Island, is an Australian external territory comprising the island of the same name. It is located in the Indian Ocean, around south of Java and Sumatra and around north-west of the ...
, and the
Palmyra Atoll
Palmyra Atoll (), also referred to as Palmyra Island, is one of the Northern Line Islands (southeast of Kingman Reef and north of Kiribati). It is located almost due south of the Hawaiian Islands, roughly one-third of the way between Hawaii a ...
. It can be distinguished by the bright violet coloration on the bottom and in a band around the middle of their tests.
Distribution and habitat
Flower urchins are widespread and common in the
tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
Indo-West Pacific
The Indo-Pacific is a vast biogeographic region of Earth.
In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...
.
They can be found north from
Okinawa
is a prefecture of Japan. Okinawa Prefecture is the southernmost and westernmost prefecture of Japan, has a population of 1,457,162 (as of 2 February 2020) and a geographic area of 2,281 km2 (880 sq mi).
Naha is the capital and largest city ...
,
Japan, to
Tasmania
)
, nickname =
, image_map = Tasmania in Australia.svg
, map_caption = Location of Tasmania in AustraliaCoordinates:
, subdivision_type = Country
, subdi ...
,
Australia in the south;
and west from the
Red Sea
The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; ...
and the
East African coast,
to
Raratonga
Rarotonga is the largest and most populous of the Cook Islands. The island is volcanic, with an area of , and is home to almost 75% of the country's population, with 13,007 of a total population of 17,434. The Cook Islands' Parliament buildings a ...
in the
Cook Islands
)
, image_map = Cook Islands on the globe (small islands magnified) (Polynesia centered).svg
, capital = Avarua
, coordinates =
, largest_city = Avarua
, official_languages =
, lan ...
in the east.
In Mexican waters, the Flower Urchin can be found in every waters of the Pacific with the exception that they are absent from
Guerrero Negro
Guerrero Negro is the largest town located in the municipality of Mulegé in the Mexican state of Baja California Sur (BCS). It had a population of 14,316 in the 2015 census. The town is served by Guerrero Negro Airport.
Whale Festival
The ...
(Bahia Tortugas),
Baja California
Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...
, northward along the central and northwest coasts of Baja.
They are found among
coral reef
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups.
C ...
s, coral rubble, rocks, sand, and
seagrass
Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the or ...
beds at depths of from the water's surface.
They may sometimes partially bury themselves on the substrate.
Ecology and behavior
Diet
Flower urchins feed on
algae,
bryozoa
Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a ...
ns, and organic detritus.
Predators
Flower urchins have few predators.
They are known to be toxic to fish. One of the few organisms capable of consuming flower urchins with no apparent adverse effects is the predatory
corallimorph ''
Paracorynactis hoplites''. However it is unknown if flower urchins are among its natural prey.
Associated species
![Lembeh Dec1809](https://upload.wikimedia.org/wikipedia/commons/5/54/Lembeh_Dec1809.jpg)
The
commensal
Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fro ...
alpheid
Alpheidae is a family of caridean snapping shrimp, characterized by having asymmetrical claws, the larger of which is typically capable of producing a loud snapping sound. Other common names for animals in the group are pistol shrimp or alpheid s ...
shrimp ''
Athanas areteformis'', can sometimes be found living among the spines of flower urchins (as well as
burrowing urchins and
collector urchins).
The
intestines
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and ...
of flower urchins can also serve as habitats for the commensal
flatworm ''
Syndesmis longicanalis''.
Flower urchins are also common hosts of the
zebra crab, ''Zebrida adamsii''. These tiny crabs are
obligate symbiont
Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...
s of sea urchins. They cling to the spines on the outer surface of the sea urchin test using their highly specialized walking legs. Because their ability to walk on substrates like sand is impaired, zebra crabs spend their entire benthic life stage attached to sea urchins, switching between hosts only during the mating season. Usually only one zebra crab is attached to an individual sea urchin outside of the mating season, but larger sea urchins can be hosts to two (very rarely more). The area of the test they inhabit is characteristically smooth; completely devoid of spines, pedicellariae, tube feet, and even epidermis. It is unknown if they physically destroy and/or consume these appendages or if they use other stimuli to induce the host sea urchins to
autotomize. Although previously considered harmless commensals, authors have since reclassified them as
parasite
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...
s. In addition to the visible external damage, a 1974 study also observed abnormal behavior and coloration among infected sea urchins. They also appear to be immune to the flower urchin's venom.
Reproduction
Flower urchins are
dioecious (having separate male and female individuals), but it is almost impossible to determine the sex of an individual by external characteristics alone. A possible method is by examining the external characteristics of the genital pores (
gonopore
A gonopore, sometimes called a gonadopore, is a genital pore in many invertebrates. Hexapods, including insects have a single common gonopore, except mayflies, which have a pair of gonopores. More specifically, in the unmodified female it is t ...
s). In males, they are generally short, cone-shaped, and extrude above the body surface; while in females they are usually sunken. However this is not reliable, as 15% of the cases can exhibit the opposite characteristics. All other external features, like shape and size of the tests or color of the spines are indistinguishable between the two sexes.
Flower urchins have a
chromosome number
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectivel ...
of
2n = 42.
Relatively little is known of the
spawning
Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquat ...
behavior of flower urchins. Like other sea urchins, fertilization happens externally. Males and females release free-swimming
gamete
A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...
s (eggs and sperm) directly into the water currents in mass spawning events.
In
Okinawa
is a prefecture of Japan. Okinawa Prefecture is the southernmost and westernmost prefecture of Japan, has a population of 1,457,162 (as of 2 February 2020) and a geographic area of 2,281 km2 (880 sq mi).
Naha is the capital and largest city ...
,
Japan, a 1994 study identified the spawning season of flower urchins as occurring in winter, at the same time as the closely related and
sympatric ''
Toxopneustes elegans''. It also recorded possible
natural hybrid
In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction. Hybrids are not always intermediates between their parents (such as in ...
s resulting from instances where the eggs of ''Toxopneustes pileolus'' are fertilized by the sperm of ''Toxopneustes elegans''.
In
Taiwan
Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...
, a 2010 study observed flower urchins spawning in May on the years 2007 and 2009. They occurred on highly similar conditions: in the afternoon
low tide of the
spring tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another.
Tide tables ca ...
immediately after a
new moon. During the event, spawning individuals discard the debris that usually cover their bodies before releasing their gametes into the water.
Another study published in 2013 did not find any obvious correlation between lunar and tidal cycles to the mass spawning behavior of the flower urchin populations in southern Taiwan. It did note that the spawning patterns appeared to be non-random, with higher spawning rates on daytime on certain dates. However, the study was conducted within a span of only five months (from April to August 2010).
"Covering" behavior
![Toxopneustes pileolus camouflage](https://upload.wikimedia.org/wikipedia/commons/c/cd/Toxopneustes_pileolus_camouflage.jpg)
Flower urchins are among the numerous species of sea urchins known as "collector urchins", so named because they frequently cover the upper surfaces of their bodies with debris from their surroundings. This behavior is usually referred to as "covering" or "heaping".
Flower urchins are usually found almost completely covered in objects like dead
coral
Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and ...
fragments,
shells,
seaweed, and rocks.
These are held fast to their bodies using their tube feet and pedicellariae.
The function of this behavior is not well understood. Some authors believe that the debris serve as
ballast
Ballast is material that is used to provide stability to a vehicle or structure. Ballast, other than cargo, may be placed in a vehicle, often a ship or the gondola of a balloon or airship, to provide stability. A compartment within a boat, ship ...
, preventing them from being swept away by wave surges when feeding;
while others believe that they may function as some sort of defense against predation.
A 2007 study has hypothesized that the behavior may serve as protection from
UV radiation
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...
during daytime.
Venom
Bioactive components
At least two active
toxin
A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849 ...
s have been purified from the pedicellarial venom of flower urchins in two studies.
The first was discovered in 1991 and named Contractin A. It was found to interfere with the transmission of signals at
nerve endings as well as cause
hemagglutination
Hemagglutination, or haemagglutination, is a specific form of agglutination that involves red blood cells (RBCs). It has two common uses in the laboratory: blood typing and the quantification of virus dilutions in a haemagglutination assay.
Blood ...
(clumping of the
red blood cell
Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...
s).
When administered to
guinea pig
The guinea pig or domestic guinea pig (''Cavia porcellus''), also known as the cavy or domestic cavy (), is a species of rodent belonging to the genus '' Cavia'' in the family Caviidae. Breeders tend to use the word ''cavy'' to describe the ...
s, it resulted in contractions in the
smooth muscles
Smooth muscle is an involuntary non-striated muscle, so-called because it has no sarcomeres and therefore no striations (''bands'' or ''stripes''). It is divided into two subgroups, single-unit and multiunit smooth muscle. Within single-unit mus ...
.
The second, discovered in 1994, is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
toxin named peditoxin. It is composed of the protein pedin and the active
prosthetic group
A prosthetic group is the non-amino acid component that is part of the structure of the heteroproteins or conjugated proteins, being tightly linked to the apoprotein.
Not to be confused with the cofactor that binds to the enzyme apoenzyme (eith ...
pedoxin. At low doses to mice, pedoxin was found to result in markedly lower body temperatures,
muscle relaxation
Muscle contraction is the activation of tension-generating sites within muscle cells. In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in muscle length, such as ...
,
sedation, and
anesthetic
An anesthetic (American English) or anaesthetic (British English; see spelling differences) is a drug used to induce anesthesia — in other words, to result in a temporary loss of sensation or awareness. They may be divided into two ...
coma. At higher doses it resulted in
convulsions and death. Pedin itself is non-toxic, but it magnifies the effects of pedoxin. When combined into the
holoprotein
A holoprotein or conjugated protein is an apoprotein combined with its prosthetic group.
Some enzymes do not need additional components to show full activity. Others require non-protein molecules called cofactors to be bound for activity. Cofact ...
peditoxin, even low doses resulted in
anaphylaxis
Anaphylaxis is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of use of emergency medication on site. It typically causes more than one of the foll ...
-like
shock
Shock may refer to:
Common uses Collective noun
*Shock, a historic commercial term for a group of 60, see English numerals#Special names
* Stook, or shock of grain, stacked sheaves
Healthcare
* Shock (circulatory), circulatory medical emergen ...
and death.
UT841, a possible third toxin isolated in 2001, has been shown to affect
brain metabolism in chicks. However, the authors are unclear on whether UT841 may actually be the same compound as Contractin A, since both have the same
molecular weight
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...
of 18,000
Da and an almost identical
N-terminal sequence.
In addition to these toxins,
lectins have also been isolated from flower urchin venom. Among them is SUL-I, SUL-II, SUL-IA, and SUL-III (SUL stands for "sea urchin lectin"). These lectins may be valuable as research tools for investigating the functions of cell processes.
Envenomation mechanism
Unlike most other venomous sea urchins, flower urchins and related
toxopneustids do not deliver their venom through spines. Instead, the venom is administered through the flower-like globiferous pedicellariae.
If undisturbed, the tips of the globiferous pedicellariae are usually expanded into round cup-like shapes. They possess tiny sensors on their inside surfaces which can detect threats by touch and chemical stimuli. When agitated or brushed against by a potential threat, the pedicellariae will immediately snap shut and inject venom. The claws of the pedicellariae may also break off from their stalks and adhere to the point of contact, retaining the ability to continually inject venom for several hours.
The potency of the pedicellarial venom is believed to be directly related to the size of the pedicellariae. Thus individuals with larger globiferous pedicellariae are considered to be more dangerous than individuals with more numerous but smaller globiferous pedicellariae.
Effects on humans
In 1930, the
Japanese
Japanese may refer to:
* Something from or related to Japan, an island country in East Asia
* Japanese language, spoken mainly in Japan
* Japanese people, the ethnic group that identifies with Japan through ancestry or culture
** Japanese diaspor ...
marine biologist
Marine biology is the scientific study of the biology of marine life, organisms in the sea. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifi ...
Tsutomu Fujiwara accidentally envenomated himself with seven or eight flower urchin pedicellariae while working in a fishing boat. He described his experience in a paper published in 1935:
There have been reports of fatalities resulting from flower urchin envenomation.
One such report was the purported drowning of a
pearl diver
Pearl hunting, also known as pearling, is the activity of recovering pearls from wild molluscs, usually oysters or mussels, in the sea or freshwater. Pearl hunting was prevalent in the Persian Gulf region and Japan for thousands of years. On the ...
after being rendered unconscious from accidental contact with a flower urchin.
But it remains difficult to confirm if these incidents actually occurred since no documentation or details of the deaths have been uncovered so far.
Nevertheless, flower urchins are still considered highly dangerous. The severe debilitating pain of the flower urchin sting compounded by muscular paralysis, breathing problems, numbness, and disorientation can result in accidental drowning among divers and swimmers.
The flower urchin was named the "most dangerous sea urchin" in the 2014 ''
Guinness World Records
''Guinness World Records'', known from its inception in 1955 until 1999 as ''The Guinness Book of Records'' and in previous United States editions as ''The Guinness Book of World Records'', is a reference book published annually, listing world ...
''.
Edibility
![Flower urchin by Vincent C Chen](https://upload.wikimedia.org/wikipedia/commons/2/28/Flower_urchin_by_Vincent_C_Chen.jpg)
Despite being venomous, flower urchins are sometimes harvested in
East Asia
East Asia is the eastern region of Asia, which is defined in both Geography, geographical and culture, ethno-cultural terms. The modern State (polity), states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. ...
,
Southeast Asia
Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainlan ...
, and the
Pacific Island
Collectively called the Pacific Islands, the islands in the Pacific Ocean are further categorized into three major island groups: Melanesia, Micronesia, and Polynesia. Depending on the context, the term ''Pacific Islands'' may refer to one of se ...
s for their
edible gonads.
In the
Sulu Archipelago of the
Philippines
The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no),
* bik, Republika kan Filipinas
* ceb, Republika sa Pilipinas
* cbk, República de Filipinas
* hil, Republ ...
and eastern
Sabah
Sabah () is a state of Malaysia located in northern Borneo, in the region of East Malaysia. Sabah borders the Malaysian state of Sarawak to the southwest and the North Kalimantan province of Indonesia to the south. The Federal Territory o ...
,
Malaysia
Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...
, flower urchins are among the species of edible sea urchins used by the
Sama-Bajau
The Sama-Bajau include several Austronesian ethnic groups of Maritime Southeast Asia. The name collectively refers to related people who usually call themselves the Sama or Samah (formally A'a Sama, "Sama people"); or are known by the exo ...
and
Tausug people to make a traditional delicacy known as ''oku-oku'' or ''ketupat tehe tehe''. This is prepared by degutting the test and then filling it with
glutinous rice and
coconut milk before boiling.
Other uses
In Okinawa, fishermen observed numerous individuals of the predatory
crown-of-thorns starfish (''Acanthaster planci'') gathering around the remains of the internal organs of flower urchins.
A follow-up study by Japanese researchers in 2001 confirmed that the
viscera
In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a f ...
of flower urchins could indeed attract crown-of-thorns starfish in both aquarium and open sea experiments. The attractant compounds were isolated and identified as
arachidonic acid and
α-linolenic acid
''alpha''-Linolenic acid (ALA), also known as α-Linolenic acid (from Greek language, Greek ''alpha'' meaning "first" and ''linon'' meaning flax), is an omega-3 fatty acid, ''n''−3, or omega-3, essential fatty acid. ALA is found in many seeds ...
. The authors believe that this discovery may be used to augment population control measures of the crown-of-thorns starfish, which are highly destructive to coral reefs.
References
External links
*
Video of a live flower urchin in its natural habitat(YouTube)
Video of a live captive flower urchin(YouTube)
Video of a flower urchin with a zebra crab(YouTube)
*
{{Taxonbar, from=Q2488394
Toxopneustidae
Fauna of the Indian Ocean
Fauna of the Pacific Ocean
Animals described in 1816
Taxa named by Jean-Baptiste Lamarck