Tropheus moorii

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Blunthead cichlid
TropheusspRed200.jpg
Tropheus moorii "Chimba"
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cichliformes
Family: Cichlidae
Genus: Tropheus
Species:
T. moorii
Binomial name
Tropheus moorii
Boulenger, 1898
Synonyms
  • Tropheus moorii mooriiBoulenger, 1898

Tropheus moorii (blunthead cichlid) is a species of cichlid endemic to Lake Tanganyika in Africa. Over 40 different color morphs of this species are dispersed throughout the lake, ranging from dark green to flame red and yellow. They mostly feed on filamentous algae on the rocky shallows they inhabit. [2] T. moorii is a maternal mouthbrooder, so eggs are fertilized and young are carried in the mouth of the female while they hatch and develop. [3]

Contents

Territorialism

Both male and female adults occupy individual feeding territories. [4] Blunthead cichlids inhabiting territories at greater depth tend to have smaller adult body sizes and larger territories compared to those in shallows. [5] Males have larger territories than females. A female leaves her territory to pair with a male and usually visits several territories multiple times before choosing a male. After the male and female form a pair bond, the female forages in his territory up to three weeks under his protection before spawning. A female's ovaries do not fully mature until she pairs with a male and feeds from his territory. After spawning, the female leaves the male's territory to occupy a small unclaimed area for the mouthbrooding period. In contrast to the frequent movement of females, a male usually remains in his territory for months even if he is never visited by females. [4]

Interspecies interactions

Often, blunthead cichlid feeding territories are adjacent to territories of conspecific and heterospecific neighbors. A male T. moorii usually courts a female conspecific, which visits his feeding territory. [5]

In Lake Tanganyika, blunthead cichlids coexist with other herbivorous cichlids P. trewavasae , P. orthognathus , P. polyodon , and T. temporalis . [2] [5] T. moorii, P. polyodon, and T. temporalis individuals are not aggressive towards one another, but are aggressive towards individuals of other species and conspecifics. Although their territories often overlap, individuals of the three species do not usually interact due to the dietary differences that exist. For example, P. polyodon and P. trewavasae mostly feed on unicellular algae rather than filamentous algae. [2]

Having overlapping territories with P. polyodon may benefit T. moorii individuals since P. polyodon removes silt from the rock surface as they feed. This allows T. moorii to easily scrape filamentous algae from the rocks. [2] Having overlapping territories with P. trewavasae may benefit T. moorii individuals because both defend their territory from much larger P. orthognathus individuals. They also are able to drive them away, whereas an individual blunthead cichlid may not be able to defend territory successfully. This is an example of commensalism rather than mutualism because individuals would defend their territories regardless. [5]

Size-dependent dominance hierarchies

T. moorii participates in size-dependent dominance hierarchies when defending territory from intruders. If an individual intrudes on a T. moorii territory, the interaction may be a one-sided (territory owner towards the intruder) attack, one-sided display (spread and quiver fins/tail to intimidate), mutual attack, or mutual displays. These usually occur at or near the borders of the territories. In a one-sided attack, the territory owner chases the intruder until it leaves the territory.

Interactions vary depending on the relative size of the territory owner and intruder. Individuals tend to perform one-sided attacks on neighbors smaller than them and perform one-sided displays towards those larger than them. Attacks may occur inside or outside the feeding territory of the territory owner, while displays usually take place within the territory. Displays are very rare when a large difference in body size (more than 2.5 cm)exists, and more common when the difference is smaller (less than 2 cm). Mutual attacks are very likely to occur when the individuals are of similar size. Neighbors (having an adjacent territory) are more likely to respond to an attack with a display compared to a non-neighbor. In observed interactions between specifically P. orthognathus and T. moorii individuals with adjacent territories, the larger fish attacked the smaller one regardless of species, and no displays occurred. [5]

Mating and reproduction

The mating system of T. moorii is serial monogamy. A male and female establish a temporary monogamous pair bond and spawn. The female mouthbroods the eggs and young with no direct assistance from the male, so after spawning, the male is free to pair bond with other females. [3] T. moorii broods show genetic monogamy, with all eggs having been fertilized by a single male. [6] Other cichlid species that exhibit similar social monogamy in mating, such as V. moorii, do not always show genetic monogamy due to parasitic spawning (males fertilizing eggs of a female paired to another male). [7] Spawning occurs on a rock surface, with the female laying up to 20 eggs which are bright orange in color. Eggs are incubated for 30 to 35 days, and when the young emerge from their mother's mouth, they are advanced enough in their physical development to live like adults. [8]

Buccal feeding

Buccal feeding refers to the feeding a mouthbrooding mother does to feed her young located in her buccal cavity. T. moorii females have unusually high parental investment in their offspring since they produce large eggs and buccally feed their young. Among cichlids, T. moorii has a very high egg to adult body size ratio. [9] In the early stages of mouthbrooding, a female rarely feeds, but after the eggs hatch, she begins feeding to nourish them. The mother effectively starves herself during the mouthbrooding period, since all nourishment she takes in goes to feed the young. [10] The yolk sacs of the eggs are depleted around the 25th day of mouthbrooding, but the offspring are not released for several more days, so in that time, all of their nourishment must come from buccal feeding. [8] Buccal feeding is costly in terms of energy for the female since it requires more swimming. Buccal feeding does not shorten the mouthbrooding period; instead, young that are fed buccally are larger, heavier, and faster than unfed young. These benefits are very advantageous to the young since they lower their predation risk and size is usually the determining factor in conflicts over resources. [9]

Sexual selection and color morphs

Two of the many variants currently included in T. moorii: "Kiriza" above and "Kachese" below. The former is part of a group informally known as T. sp. "Black" (also including "Bemba", "Bulu Point", "Lueba" and others), which may represent a separate species Tropheus.jpg
Two of the many variants currently included in T. moorii: "Kiriza" above and "Kachese" below. The former is part of a group informally known as T. sp. "Black" (also including "Bemba", "Bulu Point", "Lueba" and others), which may represent a separate species

Since male blunthead cichlids provide no brood care or other parental investment after spawning, the operational sex ratio in a population is strongly biased towards males. A male's reproductive success varies based on how many times he can mate during his life. Females, by discriminating between males to decide a mate, strongly influence male reproductive success. Experimentally, females have been shown to share preferences for the same males when given two to choose from, meaning some males get to reproduce more often than others. [3]

T. moorii shows very great diversity in color morphs, and color morph is a typical target for mate choice sexual selection. [3] A female is more likely to choose a mate that has the same morph she does and this is probably what drove the proliferation and maintenance of the many color morphs. [12] T. moorii individuals of a particular color morph are usually found in the same geographic area, so color morphs are also maintained by the relative isolation of T. moorii populations. [8] There is a level of genetic differences between some populations, and it is possible that these (notably the so-called Tropheus sp. "Black" and Tropheus sp. "Mpimbwe") represent separate species. [11]

Sexual differences

As a sexually monomorphic species, T. moorii can be quite challenging to sex. The upper lip of males is more prominent (i.e., larger) than that of females. Males' lips on average tend to be more off-white, as well, due to their constant lip-locking aggression. Furthermore, males tend to have a turned-up nose, while females tend to have a greater slope and rounded nose, making the shape of their heads ellipsoid. Males generally grow at a faster rate and display their adult colors sooner. Males' coloration is also often more bold than females' because they display when courting females. Adult males also tend to have a deeper body, whereas females appear more slim and streamlined.[ citation needed ]

Feeding and habitat

T. moorii is strictly herbivorous like all Tropheus species. They spend the majority of their time scraping algae from the rocks. In the wild, blunthead cichlids are found in shallow bays and in the upper reaches of the lake over rocky reefs where the water is quite illuminated, because this is where the algae and other vegetable matter grow most thickly. Consequently, they are adapted to bright light. [ citation needed ]

Etymology

The specific name honours the discoverer of this species, John Edmund Sharrock Moore (1870-1947). [13]

Related Research Articles

<span class="mw-page-title-main">Cichlid</span> Family of fishes

Cichlids are fish from the family Cichlidae in the order Cichliformes. Traditionally Cichlids were classed in a suborder, the Labroidei, along with the wrasses (Labridae), in the order Perciformes, but molecular studies have contradicted this grouping. On the basis of fossil evidence, it first appeared in Tanzania during the Eocene epoch, about 46–45 million years ago. The closest living relative of cichlids is probably the convict blenny, and both families are classified in the 5th edition of Fishes of the World as the two families in the Cichliformes, part of the subseries Ovalentaria. This family is large, diverse, and widely dispersed. At least 1,650 species have been scientifically described, making it one of the largest vertebrate families. New species are discovered annually, and many species remain undescribed. The actual number of species is therefore unknown, with estimates varying between 2,000 and 3,000.

<span class="mw-page-title-main">Lake Tanganyika</span> Rift lake in east-central Africa

Lake Tanganyika is an African Great Lake. It is the second-oldest freshwater lake in the world, the second-largest by volume, and the second-deepest, in all cases after Lake Baikal in Siberia. It is the world's longest freshwater lake. The lake is shared among four countries—Tanzania, the Democratic Republic of the Congo (DRC), Burundi, and Zambia, with Tanzania (46%) and DRC (40%) possessing the majority of the lake. It drains into the Congo River system and ultimately into the Atlantic Ocean.

<span class="mw-page-title-main">Mouthbrooder</span> Animal that cares for its offspring by holding them its mouth

Mouthbrooding, also known as oral incubation and buccal incubation, is the care given by some groups of animals to their offspring by holding them in the mouth of the parent for extended periods of time. Although mouthbrooding is performed by a variety of different animals, such as the Darwin's frog, fish are by far the most diverse mouthbrooders. Mouthbrooding has evolved independently in several different families of fish.

<span class="mw-page-title-main">Convict cichlid</span> Species of fish

The convict cichlid is a fish species from the family Cichlidae, native to Central America, also known as the zebra cichlid. Convict cichlids are popular aquarium fish and have also been the subject of numerous studies on fish behaviour.

<i>Julidochromis</i> Genus of fishes

Julidochromis is a genus of cichlids in the subfamily Pseudocrenilabrinae. They are commonly called julies and are endemic to Lake Tanganyika in eastern Africa. This genus includes six formally described species, some with a number local variants of uncertain taxonomic status. Further taxonomic work is required to determine how many species exist; the closely related Chalinochromis with two more species is sometimes included here and this may be correct. Hybridization makes attempts to determine relationships with molecular phylogenetic methods difficult.

<span class="mw-page-title-main">Pair bond</span> Biological term

In biology, a pair bond is the strong affinity that develops in some species between a mating pair, often leading to the production and rearing of young and potentially a lifelong bond. Pair-bonding is a term coined in the 1940s that is frequently used in sociobiology and evolutionary biology circles. The term often implies either a lifelong socially monogamous relationship or a stage of mating interaction in socially monogamous species. It is sometimes used in reference to human relationships.

<span class="mw-page-title-main">Nile tilapia</span> Species of fish

The Nile tilapia is a species of tilapia, a cichlid fish native to parts of Africa and the Levant, particularly Israel and Lebanon. Numerous introduced populations exist outside its natural range. It is also commercially known as mango fish, nilotica, or boulti.

<i>Variabilichromis moorii</i> Species of fish

Variabilichromis moorii has no common name and is a species of freshwater cichlid endemic to Lake Tanganyika in eastern Africa. It is a small ovate bodied fish named for an early collector of fish from the lake, John Edmund Sharrock Moore (1870-1947) who was a cytologist, zoologist and led an expedition to Lake Tanganyika and who discovered this species. Juveniles are usually yellow, and adults are dark brown to black in color. It reaches a total length (TL) of 10.3 centimetres (4.1 in). Currently it is the only member of its genus. V. moorii feeds on algae, zooplankton, and benthic invertebrates. It is also found in the aquarium trade.

<i>Tropheus</i> Genus of fishes

Tropheus is a small genus of at least six species of cichlids endemic to Lake Tanganyika in East Africa. The genus is widespread across all regions of Lake Tanganyika, from Burundi in the north to Zambia in the south. Males and females are relatively similar in color, with only subtle sexual dimorphism in the form of the male's larger size. All species are maternal mouthbrooders, with the females caring for their eggs and fry in their mouths; this characteristic provides their generic name, Tropheus, which comes from the Greek trophos, which means "to nurse" or, according to Boulenger, "one who rears, brings up, educates". The genus is fished lightly by the local population, but has never become a staple food fish due to its relatively small size and its habitat, which enables it to dart between rocks when threatened.

<span class="mw-page-title-main">Rainbow cichlid</span> Species of fish

Herotilapia multispinosa also known as the rainbow cichlid is a Central American freshwater fish of the cichlid family. It is found on the Atlantic slope of Honduras, Nicaragua, and Costa Rica from Patuca River (Honduras) south to Matina River, and on the Pacific slope of Nicaragua and Costa Rica from Guasaule River south to Tempisque River. Specimens are also reported from the Choluteca River on the Pacific side of Honduras. This species is found in lakes and swamps with muddy bottoms, where it uses its specialized teeth and only 3.5% jaw protrusion to feed mostly on algae. It is commercially important as an aquarium fish. The rainbow cichlid prefers a pH range of 7.0–8.0, water hardness of 9-20 dGH and a temperature range of 21–36 °C.

<span class="mw-page-title-main">Mozambique tilapia</span> Species of fish

The Mozambique tilapia is an oreochromine cichlid fish native to southeastern Africa. Dull colored, the Mozambique tilapia often lives up to a decade in its native habitats. It is a popular fish for aquaculture. Due to human introductions, it is now found in many tropical and subtropical habitats around the globe, where it can become an invasive species because of its robust nature. These same features make it a good species for aquaculture because it readily adapts to new situations. It is known as black tilapia in Colombia and as blue kurper in South Africa.

<i>Synodontis multipunctatus</i> Species of fish

Synodontis multipunctatus, also known as the cuckoo catfish, cuckoo squeaker, or multipunk, is a small catfish from Lake Tanganyika, one of the lakes in the Great Rift Valley system in Africa. It is a brood parasite upon mouthbrooding cichlids. This species grows to a length of 27.5 centimetres (10.8 in) TL. This species is a minor component of local commercial fisheries.

<i>Copadichromis borleyi</i> Species of fish

Copadichromis borleyi is a species of haplochromine cichlid fish endemic to Lake Malawi in East Africa. The species is popular in the fishkeeping hobby where it is frequently kept in aquariums. The species has numerous common names, including redfin hap and goldfin hap.

<i>Ctenochromis horei</i> Species of fish

Ctenochromis horei is a species of haplochromine cichlid which is found in East Africa.

<i>Cyprichromis leptosoma</i> Species of fish

Cyprichromis leptosoma is a mouthbrooding species of fish in the family Cichlidae. It is endemic to Lake Tanganyika in Zambia and Tanzania. It seems quite common within its range and faces no particular threats, so the International Union for Conservation of Nature has assessed its conservation status as being of least concern.

<span class="mw-page-title-main">Malawi eyebiter</span> Species of fish

The Malawi eyebiter is a species of fish in the family Cichlidae. This predatory cichlid is endemic to Lake Malawi in East Africa.

<i>Gnathochromis pfefferi</i> Species of fish

Gnathochromis pfefferi is an African species of fish in the family Cichlidae. It is endemic to Lake Tanganyika and its slow-flowing tributaries in the countries of Burundi, the Democratic Republic of the Congo, Tanzania and Zambia. It is common and widespread. This cichlid is found in relatively shallow waters, typically over soft bottoms in places with aquatic grasses.

<i>Astatotilapia burtoni</i> Species of fish

Astatotilapia burtoni is a species of fish in the family Cichlidae.

<i>Petrochromis polyodon</i> Species of fish

Petrochromis polyodon is a species of cichlid endemic to Lake Tanganyika found in areas with rocky substrates where it can graze on algae. This species coexists with other herbivorous cichlids such as Tropheus moorii and Telmatochromis temporalis. Individuals can reach lengths of 40cm or 16 inches and 1kg in weight. They can be found in the aquarium trade.

<span class="mw-page-title-main">Ritualized aggression</span>

Ritualized aggression or ritualized fighting is when animals use a range of behaviours as posture or warning but without engaging in serious aggression or fighting, which would be expensive in terms of energy and the risk of injury. Ritualized aggression involves a graded series of behaviours or displays that include threatening gestures and occasionally posturing physical actions such as inhibited (non-injurious) bites.

References

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