Thor amboinensis

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Thor amboinensis
Squat shrimp Nick Hobgood.jpg
Scientific classification
T. amboinensis
Binomial name
Thor amboinensis
(de Man, 1888)  [1]
Synonyms   [1]
  • Hippolyte amboinensisde Man, 1888
  • Thor discosomatisKemp, 1916

Thor amboinensis, commonly known as the squat shrimp or sexy shrimp, is a species of shrimp found across the Indo-West Pacific and in parts of the Atlantic Ocean. It lives symbiotically on corals, sea anemones and other marine invertebrates in shallow reef communities. [2]

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 sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more closely they represent problematic species concepts. For example, the boundaries between closely related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, and in a ring species. Also, among organisms that reproduce only asexually, the concept of a reproductive species breaks down, and each clone is potentially a microspecies.

Caridea Infraorder of shrimp

The Caridea, commonly known as caridean shrimp, are an infraorder of shrimp within the order Decapoda. They are found widely around the world in both fresh and salt water.

Indo-Pacific A biogeographic region of the Earths seas, comprising the tropical waters of the western Pacific Ocean, the eastern Indian Ocean, and the connecting seas.

The Indo-Pacific, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, is a biogeographic region of Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia. It does not include the temperate and polar regions of the Indian and Pacific oceans, nor the Tropical Eastern Pacific, along the Pacific coast of the Americas, which is also a distinct marine realm.



Thor amboinensis is a small shrimp growing to a length of about 13 millimetres (0.5 in). It is an olive brown colour with symmetrically placed white patches edged with thin blue lines. It characteristically carries its abdomen curved upwards with its tail fan above its head. [3]


Though it is named for Ambon or Amboyna Island, one of the Maluku Islands in Indonesia, Thor amboinensis has a pantropical distribution being found in the Red Sea, the Indian Ocean, the Pacific Ocean, the Caribbean Sea, the Gulf of Mexico, Madeira and the Canary Islands. [1]

Ambon Island island

Ambon Island is part of the Maluku Islands of Indonesia. The island has an area of 775 km2 (299 sq mi) and is mountainous, well watered, and fertile. Ambon Island consists of two territories - the city of Ambon to the south and various districts (kecamatan) of the Central Maluku Regency to the north. The main city and seaport is Ambon, which is also the capital of Maluku province, while those districts of Maluku Tengah Regency situated on Ambon Island had a 2014 population of 132,377. Ambon has an airport and is home to the Pattimura University and Open University, state universities, and a few private universities, which include Darussalam University and Universitas Kristen Indonesia Maluku (UKIM).

Maluku Islands archipelago within Indonesia

The Maluku Islands or the Moluccas are an archipelago in eastern Indonesia. Tectonically they are located on the Halmahera Plate within the Molucca Sea Collision Zone. Geographically they are located east of Sulawesi, west of New Guinea, and north and east of Timor.


Thor amboinensis forms a commensal relationship with another invertebrate, usually a shallow water sea anemone or mushroom coral. [4] The species most often used as host in Bermuda include the carpet anemone ( Stichodactyla haddoni ), the stinging anemone ( Lebrunia danae ) and the adhesive anemone ( Cryptodendrum adhaesivum ). One or several shrimps live among the tentacles of their host, feeding on the tentacle tissue and on the mucus-trapped planktonic particles adhering to it. [5] In the Bahamas, Thor amboinensis forms part of an assemblage of symbiotic invertebrates associated with the anemone Lebrunia danae. Each shrimp, crab and brittle star inhabits its own part of the sea anemone and Thor amboinensis is found hidden deep among the pseudotentacles. [6]

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 from each other, amensalism, where one is harmed while the other is unaffected, and parasitism, where one benefits while the other is harmed. The commensal may obtain nutrients, shelter, support, or locomotion from the host species, which is substantially unaffected. The commensal relation is often between a larger host and a smaller commensal; the host organism is unmodified, whereas the commensal species may show great structural adaptation consonant with its habits, as in the remoras that ride attached to sharks and other fishes. Remoras feed on their hosts' fecal matter, while pilot fish feed on the leftovers of their hosts' meals. Numerous birds perch on bodies of large mammal herbivores or feed on the insects turned up by grazing mammals.

Host (biology) Organism that harbours another organism

In biology and medicine, a host is an organism that harbours a parasitic, a mutualistic, or a commensalist guest (symbiont), the guest typically being provided with nourishment and shelter. Examples include animals playing host to parasitic worms, cells harbouring pathogenic (disease-causing) viruses, a bean plant hosting mutualistic (helpful) nitrogen-fixing bacteria. More specifically in botany, a host plant supplies food resources to micropredators, which have an evolutionarily stable relationship with their hosts similar to ectoparasitism. The host range is the collection of hosts that an organism can use as a partner.

Bermuda British overseas territory in the North Atlantic Ocean

Bermuda is a British Overseas Territory in the North Atlantic Ocean. It is approximately 1,070 km (665 mi) east-southeast of Cape Hatteras, North Carolina; 1,236 km (768 mi) south of Cape Sable Island, Nova Scotia; and 1,759 km (1,093 mi) northeast of Cuba. The capital city is Hamilton. Bermuda is self-governing, with its own constitution and government and a Parliament which makes local laws. The United Kingdom retains responsibility for defence and foreign relations. As of July 2018, its population is 71,176, the highest of the British overseas territories.

Life cycle

The female Thor amboinensis carries the fertilised eggs under her abdomen until they are ready to hatch. The zoea larvae pass through several stages and, before undergoing metamorphosis, are attracted by both chemical cues in the water and visual cues which cause them to settle near potential host anemones. [7] Researchers found that the larvae of Thor amboinensis were generalists, being attracted by and accepting several different species of anemone as hosts. In some experiments they had a preference for the species of anemone from which the parent shrimp had been collected. [8]

Metamorphosis profound change in body structure during the postembryonic development of an organism

Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some insects, fishes, amphibians, mollusks, crustaceans, cnidarians, echinoderms, and tunicates undergo metamorphosis, which is often accompanied by a change of nutrition source or behavior. Animals that go through metamorphosis are called metamorphoses. Animals can be divided into species that undergo complete metamorphosis ("holometaboly"), incomplete metamorphosis ("hemimetaboly"), or no metamorphosis ("ametaboly").


Thor amboinensis is a popular species for marine aquaria. Sexy shrimp are often kept in groups of three or more, due to their small size, a quality that also makes them popular nano reef inhabitants. They will readily host in any anemones present in the aquarium and if an anemone is not available, may host in certain types of coral. Sexy shrimp will scavenge for meaty food scraps, like mysis shrimp, clam, and other prepared fish foods. If a host cnidarian is present, they may feed on the host's mucous. [9] [10]

Related Research Articles

Reef safe is a distinction used in the saltwater aquarium hobby to indicate that a fish or invertebrate is safe to add to a reef aquarium. There is no fish that is completely reef safe. Every fish that is commonly listed as reef safe are species that usually do not readily consume small fish or invertebrates. Fish listed as reef safe also do not bother fellow fish unless in some cases, for instance tangs, they do not get along with conspecifics and sometimes fish with similar color or body shape. Every fish has a personality, is different, and, in some cases, are opportunistic feeders. Tangs, which by most accounts are reef safe, may in adulthood eat some crustaceans shortly after they molt. Many larger predatory fish, for instance eels and pufferfish, will adapt very well to a reef tank and will be problem-free as long as they have sizable tank-mates and no crustaceans. Some aquarists have also had success in keeping smaller fish with predatory ones in reef tanks by adding the smaller fish at night, sometimes with newly rearranged rockwork.

<i>Heteractis magnifica</i> Heteractis magnifica is a sea anemone of the family Stichodactylidae.

Heteractis magnifica, also known by the common names magnificent sea anemone or Ritteri anemone, is a species of sea anemone belonging to the Stichodactylidae family native to the Indo-Pacific area.

Cinnamon clownfish species of fish

Amphiprion melanopus, also known as the cinnamon clownfish, fire clownfish, red and black anemonefish, black-backed anemonefish or dusky anemonefish is a widely distributed anemonefish chiefly found in the western and southern parts of the Pacific Ocean.. The species scientific name 'melanopus' is Greek, meaning black feet in reference to the black pelvic fins. Like all anemonefishes it forms a symbiotic mutualism with sea anemones and is unaffected by the stinging tentacles of the host anemone. It is a sequential hermaphrodite with a strict sized based dominance hierarchy: the female is largest, the breeding male is second largest, and the male non-breeders get progressively smaller as the hierarchy descends. They exhibit protandry, meaning the breeding male will change to female if the sole breeding female dies, with the largest non-breeder becomes the breeding male.

<i>Lysmata amboinensis</i> species of crustacean

Lysmata amboinensis is an omnivorous shrimp species known by several common names including the Pacific cleaner shrimp. It is considered a cleaner shrimp as eating parasites and dead tissue from fish makes up a large part of its diet. The species is a natural part of the coral reef ecosystem and is widespread across the tropics typically living at depths of 5–40 metres (16–131 ft).

Spotted cleaner shrimp species of crustacean

The spotted cleaner shrimp, is a kind of cleaner shrimp common to the Caribbean Sea. These shrimp live among the tentacles of several species of sea anemones. They sway their body and wave their antennae in order to attract fish from which they eat dead tissue, algae and parasites.

<i>Stenorhynchus seticornis</i> species of crustacean

Stenorhynchus seticornis, the yellowline arrow crab or simply arrow crab, is a species of marine crab.

Tomato clownfish species of fish

The tomato clownfish is a species of marine fish in the family Pomacentridae, the clownfishes and damselfishes. It is native to the waters of the Western Pacific, from the Japan to Indonesia. Other common names include blackback anemonefish, bridled anemonefish, fire clown, and red tomato clown.

Bubble-tip anemone species of cnidarian

Bubble-tip anemone is a species of sea anemone in the family Actiniidae. Like several anemone species, E. quadricolor can support several anemonefish species, and displays two growth types based on where they live in the water column, one of which gives it the common name, due to the bulbous tips on its tentacles.

<i>Stichodactyla haddoni</i> species of cnidarian

Stichodactyla haddoni, commonly known as Haddon's sea anemone, is a species of sea anemone belonging to the family Stichodactylidae. It is found in the Indo-Pacific area.

<i>Aiptasia</i> genus of cnidarians

Aiptasia is a genus of a symbiotic cnidarian belonging to the class Anthozoa. Aiptasia is a widely distributed genus of temperate and tropical sea anemones of benthic lifestyle typically found living on mangrove roots and hard substrates. These anemones, as well as many other cnidarian species, often contain symbiotic dinoflagellate unicellular algae of the genus Symbiodinium living inside nutritive cells. The symbionts provide food mainly in the form of lipids and sugars produced from photosynthesis to the host while the hosts provides inorganic nutrients and a constant and protective environment to the algae. Species of Aiptasia are relatively weedy anemones able to withstand a relatively wide range of salinities and other water quality conditions. In the case of A. pallida and A. pulchella, their hardiness coupled with their ability to reproduce very quickly and out-compete other species in culture gives these anemones the status of pest from the perspective of coral reef aquarium hobbyists. These very characteristics make them easy to grow in the laboratory and thus they are extensively used as model organisms for scientific study. In this respect, Aiptasia have contributed a significant amount of knowledge regarding cnidarian biology, especially human understanding of cnidarian-algal symbioses, a biological phenomenon crucial to the survival of corals and coral reef ecosystems. The dependence of coral reefs on the health of the symbiosis is dramatically illustrated by the devastating effects experienced by corals due to the loss of algal symbionts in response to environmental stress, a phenomenon known as coral bleaching.

Snakelocks anemone species of cnidarian

The snakelocks anemone is a sea anemone found in the eastern Atlantic Ocean and the Mediterranean Sea. The latter population is however sometimes considered a separate species, the Mediterranean snakelocks anemone.

Sea anemone Order of cnidarians

Sea anemones are a group of marine, predatory animals of the order Actiniaria. They are named after the anemone, a terrestrial flowering plant, because of the colourful appearance of many. Sea anemones are classified in the phylum Cnidaria, class Anthozoa, subclass Hexacorallia. As cnidarians, sea anemones are related to corals, jellyfish, tube-dwelling anemones, and Hydra. Unlike jellyfish, sea anemones do not have a medusa stage in their life cycle.

<i>Condylactis gigantea</i> species of cnidarian

Condylactis gigantea is a tropical species of ball anemone that is found in shallow reefs and other shallow inshore areas in the Caribbean Sea – more specifically the West Indies – and the western Atlantic Ocean including southern Florida through the Florida Keys. It is also commonly known as: giant Caribbean sea anemone, giant golden anemone, condylactis anemone, Haitian anemone, pink-tipped anemone, purple-tipped anemone, and Florida condy. This species can easily be seen growing in lagoons or in inner reefs as either individuals or loose groups, but never as colonies. They are often used as a model organism along with others in their genus for facultative symbiosis with monocellular algae.

<i>Ancylomenes pedersoni</i> species of crustacean

Ancylomenes pedersoni, sometimes known as Pederson's shrimp, is a species of cleaner shrimp. It is part of the genus Ancylomenes and was described in 1958 by Fenner A. Chace Jr. as Periclimenes pedersoni. Ancylomenes pedersoni is found in the Caribbean Sea, often associated with a sea anemone, at depths of 1 to 15 metres. They are often found on the reefs off Bermuda.

<i>Bartholomea annulata</i> species of cnidarian

Bartholomea annulata is a species of sea anemone in the family Aiptasiidae, commonly known as the ringed anemone or corkscrew anemone. It is one of the most common anemones found on reefs in the Caribbean Sea.

<i>Lebrunia neglecta</i> species of cnidarian

Lebrunia neglecta is a species of sea anemone in the family Aliciidae. It is found in the Caribbean Sea and Gulf of Mexico.

Mithraculus cinctimanus is a species of crab in the family Majidae. It is found in the Caribbean region and is usually associated with a sea anemone, sponge or coral.

<i>Cryptodendrum</i> species of cnidarian

Cryptodendrum is a genus of sea anemones in the family Thalassianthidae. It is monotypic with a single species, Cryptodendrum adhaesivum, also commonly known as the adhesive anemone, pizza anemone, and nap-edged anemone. Like all symbiotic anemones it hosts zooxanthellae, symbiotic algae that help feed their host.

<i>Lebrunia coralligens</i> species of cnidarian

Lebrunia coralligens, commonly known as the hidden anemone, is a species of sea anemone in the family Aliciidae. It is found in shallow water in the Bahamas, the Caribbean, and Brazil. It lives in fissures in corals and rocks.


  1. 1 2 3 Sammy De Grave, Charles Fransen & Michael Türkay (2013). "Thor amboinensis (De Man, 1888)". World Register of Marine Species . Retrieved October 25, 2013.
  2. A. J. Bruce (1984). "Marine caridean shrimps of the Seychelles". In David Ross Stoddart (ed.). Biogeography and ecology of the Seychelles Islands. Springer. pp. 141–169. ISBN   978-90-6193-107-2.
  3. Ruzanski, Genna; Wood, James. "Squat Shrimp (Thor amboinensis)". Marine Invertebrates of Bermuda. Retrieved 30 November 2014.
  4. Bos AR, Hoeksema BW (2015). "Cryptobenthic fishes and co-inhabiting shrimps associated with the mushroom coral Heliofungia actiniformis (Fungiidae) in the Davao Gulf, Philippines". Environmental Biology of Fishes. 98 (6): 1479–1489. doi:10.1007/s10641-014-0374-0.
  5. Genna Ruzanski. "Squat shrimp (Thor amboinensis)". Marine Invertebrates of Bermuda. Retrieved 2012-10-17.
  6. William Herrnkind, Gregg Stanton & Edwin Conklin (1976). "Initial characterization of the commensal complex associated with the anemone, Lebrunia danae, at Grand Bahama". Bulletin of Marine Science . 26 (1): 65–71.
  7. Dale Sarver (1979). "Larval culture of the shrimp Thor amboinensis (De Man, 1888) with reference to its symbiosis with the anemone Antheopsis papillosa (Kwietniewski, 1898)". Crustaceana . Suppl. 5: 176–178. JSTOR   25027500.
  8. Chau-Chih Guo, Jiang-Shiou Hwang & Daphne Gail Fautin (1996). "Host selection by shrimps symbiotic with sea anemones" (PDF). Journal of Experimental Marine Biology and Ecology . 202 (2): 165–176. doi:10.1016/0022-0981(96)00020-2.
  9. Aspinall, Richard. "Keeping Sexy Shrimp". Tropical Fish Hobbyist Magazine (August 2012): 95. Retrieved 23 November 2014.
  10. "Sexy Shrimp". Microcosm Aquarium Explorer. Microcosm Ltd. Retrieved 23 November 2014.