The swollen thorn acacia (Acacia cornigera) is distributed throughout Central America
entwined in an obligatory mutualistic relationship with a species of acacia ant
(Pseudomyrmex ferruginea). Plant
species that have colonies of ants living within the internal and external
structures have been given the term myrmecophytes (Janzen, 1966). The acacia ant and plant
provides essential benefits for each symbiont concerning protective and
reproductive purposes.
The swollen thorn acacias acquire their name from key characteristic
features including: enlarged stipular thorns, enlarged foliar nectaries,
modified leaflet tips known as Beltian bodies which are consumed by the ants, and
year round leaf production. It is to be noted that the obligate acacia ants are
not species specific rather to the swollen acacia life form (Janzen, 1966). Initially a queen ant is attracted
by a distinct odour and selects to nest inside the tree, specifically the
hollow acacia horns. The queen then lays her eggs within the hollowed thorn
whereby they hatch and become the first generation workers, the colony
continues growing in size to adequately provide protection for the acacia from many insects and mammals that may wish to feed on the plant. The ants repel
epiphytic vines by sectioning tendrils that come into contact with the acacia. A. cornigera provides sugar rich nectar
from nectaries and beltian bodies which are collected and stored by the ants as
a food resource for the ant larvae. The ants have also been known to remove
small seedlings around the base of the acacia as potential competitors for
sunlight and other essential resources (Risch et al., 1977).
The acacia ant colonies are continuously increasing in size
until a population of over 4000 exists which takes a minimum of three years to
establish. In recent experiments it has been shown that an acacia plant will
become subject to large amounts of damage from herbivorous behaviour if the pair are separated (Hölldobler,
1990).
The benefits each receive from the relationship are essential to each symbionts
survival and success.
A recently
discovered mutualistic relationship exists between 3 species of Nepenthes genus carnivorous pitcher
plants and the mountain treeshrew (Tupaia
montana). In this blog I will focus specifically on the Rajah Pitcher Plant
(Nepenthes rajah) and the mountain
treeshrew which are located and endemic to the tropical regions of Borneo (Greenwood et
al., 2011).
These
pitchers are distributed in nutrient deficient substrates in which its
acquisition of essential nutrients such as nitrogen and phosphorus cannot be
sourced via the typically method seen in most species of plants. These three
species have shown to dominate the specialized acquisition of nutrients away
from the typical arthropod trapping strategies (Moran et al.,
2003). Each have developed certain
attributes which specifically attract the montane treeshrew in the rather
unusual mutualistic relationship in which the treeshrew defecates into the Nepenthes’ pitchers. The treeshrew does
this whilst visiting the pitchers to access the delicious secretions from the
strategically positioned pitchers lids which is rich in carbohydrates (Greenwood et
al., 2011). The Rajah Pitcher has had some
interesting studies conducted investigating the pitcher geometry. It was found that
the distance from the front of the pitchers digestive organ to the secretionary
glands is exactly that of the treeshrews head to body length. The only way for
the treeshrew to access the delicious secretions is to orientate its self so
its rear is hovering above the pitchers mouth in which it defecates into as a
marking of feeding territory (Walker, 2010).
Figure 1. Photographer: Chien Lee (2011) Rajah pitcher plant (Nepenthes rajah) with Mountain Treeshrew (Tupaia montana).
A study
conducted by Greenwood, et at. 2011, indicated that more than one species of
mammal visits the pitchers. A small number of mammals visit the N. rajah during daylight and night
periods with the treeshrew only visiting in daylight hours whilst a small rat
species (Rattus baleunsis) was seen
to visit both during nocturnal and diurnal hours. It was found that sugar
concentrations of the secretions do not significantly differ in neither day nor
night period suggesting that multidirectional resource-based mutualism
between a mammal and a carnivorous plant which is the second known example
discovered. It was also discovered the N.
rajah is the first species of the Nepenthes
species to benefit from nocturnal and diurnal mammalian faecal input (Greenwood et al., 2011).
T. montana is also
known to display a relatively simply intestinal morphology which results in moderately
short digestion tract and passage time which causes the treeshrews to regularly
defecate in time periods no longer than one hour which is largely beneficial
for N. rajah (Emmons, 2000).
The down side to this is that the nutrient extraction within the treeshrew
through the intestinal tract is low and causes an increase in nutrient content
in the excreted in the scats. This is suggested to be the reason they visit
these pitchers so vigorously to supplement their diet and gain the essential
nutrients they require (Clarke et al., 2009).
A very interesting relationship exists between these two
symbionts with a large amount of room for further scientific investigation to
uncover more of the unusual mutualism and the benefits each receive. The below video shows a treeshrew accessing secretions from N. rajah and depositing excrement.
Video with thanks to BBC Earth
https://www.youtube.com/watch?v=TwL7K_loRjM
References:
CLARKE, C. M.,
BAUER, U., CH'IEN, C. L., TUEN, A. A., REMBOLD, K. & MORAN, J. A. 2009.
Tree shrew lavatories: a novel nitrogen sequestration strategy in a tropical
pitcher plant. Biology Letters, 5, 632-635.
EMMONS, L. 2000. Tupai: a
field study of Bornean treeshrews, Univ of California Press.
GREENWOOD, M., CLARKE, C., CH'IEN, C. L., GUNSALAM, A. & CLARKE,
R. H. 2011. A unique resource mutualism between the giant Bornean pitcher
plant, Nepenthes rajah, and members of a small mammal community. PLoS One, 6, e21114.
MORAN, J. A., CLARKE, C. M. & HAWKINS, B. J. 2003. From
carnivore to detritivore? Isotopic evidence for leaf litter utilization by the
tropical pitcher plant Nepenthes ampullaria. International Journal of Plant Sciences, 164, 635-639.
The famously known clownfish and anemone are a classic
example of an obligatory mutualistic relationship. 10 species of anemone coexists
with the 26 species of tropical clownfish. Within this only select pairs of
anemone and clownfish are compatible; some species specific (Fautin, 1991).
The individuals involved in the mutualistic relationships are known as obligatory
symbionts which means they are highly dependent on each other; for a variety of
beneficial reason including protection from predators, exchange of nutrients
and protection from nematocyst strikes from the anemone (Fautin, 1991).
Figure 1. Photographer: Samuel Chow (2007). Clownfish protected by tentacles of anemone in obligatory mutualistic relationship.
This relationship is exclusively observed in shallow waters
of the tropical Indo-Pacific, typically on or near coral reefs. In nearly all
cases, an individual sea anemone or a cluster of contiguous ones is inhabited
by an adult pair of anemone fish and, depending on the species of fish, in some
cases by one or more juveniles (Dunn, 1981).
Reproductive behaviour is constituted by both parental figures, though predominantly
male orientated. The eggs are laid on
the substratum beside the anemone, and whereby the male regularly exercises mouthing and
fanning the eggs to keep them clean and supplying constant oxygenated water; he
also removes the unfertilised eggs from the clutch to further increase the success
rate of the incubating young (Allen, 1972):(Dhaneesh et al., 2009).
Anemones possess tentacles that are covered in nematocysts
which are characteristic to scyphozoan and
other cnidarians. Nematocyst strikes
from the anemone paralyse almost any small marine organisms that comes into
contact with the tentacles. They are spear like stingers that when mechanically
or chemically stimulated fire and penetrate into a foreign object and release a
paralysing toxin into the blood stream of the organism; the anemone is then
able to digest the food (Nematocyst, 2015). Some fish try to feed on the
nutrient rich tentacles of the anemone in which the clown fish’s aggression and
territorial behaviour warns them off and if that fails they risk being stung by
the nematocysts (Fautin, 1991).
Figure 2. Author: unknown. Firing of a nematocyst used by cnidarians for feeding
Clownfish are believed to be protected by a mucus coating
produced that prevents nematocysts strikes against them. Some studies have
suggested the protective feature can be of various nature including: innate, acquired
or both. Some species of clownfish are suggested to be innately protected by
the mucus before ever coming into contact with the anemone while other species
are suggested to have an acquired mode of protection. This is seen in the
behaviour of the clownfish by repeated brushing through the tentacles of the
anemone to acclimate to the host before clownfish can move freely throughout
the anemone. The clownfish then acquires antigens that act as a chemical camouflage
preventing the nematocysts from firing (Fautin, 1991).
The anemone and clownfish actively participate in the mutualistic
relationship as obligatory symbionts providing essential and beneficial natural
services for each individual.
References:
ALLEN, G. R. 1972. The Anemonefishes: their Classification
and Biology (Neptune City, N. J., T. F. H. Publ., Inc. Ltd.).
DHANEESH, K.,
KUMAR, T. A. & SHUNMUGARAJ, T. 2009. Embryonic development of percula
clownfish, Amphiprion percula (Lacepede, 1802). Middle-East J. Sci. Res, 4,
84-89.
DUNN, D. F. 1981. The Clownfish Sea Anemones: Stichodactylidae (Coelenterata:
Actiniaria) and Other Sea Anemones Symbiotic with Pomacentrid Fishes. Transactions of the American Philosophical
Society, 71, 3-115.
FAUTIN, D. G. 1991. The anemonefish symbiosis: what is known and
what is not.
Figure 1. Samuel Chow (2007). Clownfish protected by tentacles of anemone in obligatory mutualistic relationship. Retrieved from http://www.asknature.org/strategy/fb410d8500af30a5daf5b647954b7fa5#menuPopup, on 29/05/2015.
Figure 2. Author:unknown (n.d) Firing of a nematocyst used by cnidarians for feeding. Retrieved from http://reefworks.co.uk/wp-content/uploads/2011/10/nematocysts-glow-small.jpg, on 29/05/2015
The bluestreak cleaner wrasse (L. dimidiatus) from the Labridae family shares
mutualistic relationships with a vast number of larger marine species,
specialising on crustacean ectoparasites and mucus. Vastly distributed throughout
shallow reef systems occupying cleaning stations associated with formations
such as coral heads and between two outcrops. This species of cleaner wrasse is
distributed throughout the Indo-Pacific from southern and eastern Africa to the
Tuamotus in the south Pacific, also from southern Japan to the Great Barrier Reef
and south-western Australia (Losey, 1972)
Coral reefs are one of the most species rich environments on earth,
they provide protection and habitat for a diverse range of sea life ranging
from large migratory mammals to small crustaceans, also a large amount of
bacteria and algae species. Cleaner wrasse encourage diversity within a coral
reef ecosystem by providing beneficial cleaning stations, typically occupied by
a group of youths, a pair of adults, or a group of females accompanied by a
dominant male. The cleaners greet the clients with an up and down motion of the
rear end and the fish respond by opening their mouths or exposing the area they
wish cleaned for example flaring their gills. In a recent experiment conducted
on the effect that cleaner wrasse have on coral reef communities it was found
that resident fish species were 37 % less abundant and 23 % reduced species
richness per reef when cleaner wrasse were removed. The investigation also showed
lower growth rate and survivorship among fish species within the community (Waldie et al., 2011).
A bluestreak fangblenny (Plagiotremus rhinorhynchos) has taken advantage
of the juvenile cleaner wrasse appearance to gain access to food, with a single blue strip down the lateral surface of the fish. The
fangblenny is found lurking around cleaning stations mimicking the appearance
and behaviour of the bluestreak cleaner wrasse, when in striking range they
ambush and use their fangs to tears pieces of flesh from client fish. They are
able to change their appearance accordingly and can be found in locations that
cleaners have not settled and occupy small crevasses and strike at shoals when
they swim by. These mimics have shown to reduce the number of clients that
enter the cleaning station which inevitably affects the feeding habits and
behaviour of the cleaner wrasse (Côté and
Cheney, 2005).
The crucial health benefits these cleaner wrasse provide in the
mutualistic relationship are very important in helping maintain species
diversity and richness in coral reef communities where a range of larger
species regularly visit. The bluestreak cleaner wrasse is not the only species
of cleaner fish that partakes in this mutualistic relationship, though is one
of the better known examples of cleaners in the marine environment.
WALDIE, P. A., BLOMBERG, S. P.,
CHENEY, K. L., GOLDIZEN, A. W. & GRUTTER, A. S. 2011. Long-term effects of
the cleaner fish Labroides dimidiatus on coral reef fish communities. PLoS one, 6, e21201.
Figure 1. Difference in species of cleaner and mimic. (n.d) Available from http://ed101.bu.edu/StudentDoc/Archives/fall05/edwardsk/blueblenny.html. Retrieved on 03/05/2015
The Sea Lamprey (Petromyzon
marinus) belongs to the order Petromyzontiformes which consists of 40 known extant species of Lamprey; 18 are
known to be parasitic. These primitive fish have an antitropical distribution in
both fresh and salt water as the young, known as ammocoete, have low thermal
tolerance and is non-viable to reproduce in such an area that cannot support offspring. As the name suggests the Sea lamprey spends its adult life occupying coastal
waters and oceans. Certain species are known to travel extensive distances for
breeding purposes up into freshwater billabongs and periodically land locked
habitats providing evidence for isolation by distance and physical barrier (Renaud,
C.B 2011).
Figure 1. The Sea Lamprey (Petromyzon marinus). Photographer: Breck P, Kent
The
lampreys are notorious for their hematophagus feeding (blood sucking) ability which is only facilitated in postmetamorphosed
individuals or the adult stage. Sea lampreys have a 3 staged life cycle
compromised of the larval, metamorphosis and parasitic stage of which their
morphology and physiology undergo drastic changes to cope with the transition
from fresh to salt water and their new feeding habits. The lamprey depend on
the parasitic relationships with their host as they require blood. They adhere and bore a hole in the flesh using their specialised circular
mouth filled with reversed keratinised teeth. Anticoagulants in saliva prevent
the host’s blood from clotting and they can maintain a constant supply of
food. They poses annular cartilage as opposed to a jaw bone that supports the
supraoral and inraoral laminae. This allows the free movement and adaptation to
different adhesion surfaces for the lamprey to anchor. The shading of teeth in
terms of colour provides an estimate to the age; typically, darkened relates to
older teeth. In relation to the age of the teeth is estimated that in a 2 year
period the lamprey will replace its teeth in the vicinity of 30 times; they
have a hollow core allowing stacked tooth structure as a fast method of teeth
renewal (Seagle, H.H. et al, 1982: Beamish, F.W.H. et al 1975)
These vampire like blood sucking creatures rely on a variety
of marine hosts in order to survive. Lampreys feeding behaviour has evolved
over millions of years and proven the test of time and have also become one of
the largest parasitic feeders in the marine ecosystem.
Video with thanks to NatGeo Wild. https://www.youtube.com/watch?v=AzZao6SVMyc
References:
Beamish, F.W.H. & Potter, I.C. 1975. The biology of the
anadromous Sea Lamprey (Petromyzon marinus) in New Brunswick. J. Zool., 177:
57–72.
Renaud, C.B. 2011 Lampreys of the world. An annotated and
illustrated catalogue of lamprey species known to date. FAO Species Catalogue
for Fishery Purposes. No. 5. Rome, FAO. 109 pp.
Seagle, H.H., Jr. & Nagel, J.W. 1982. Life cycle and
fecundity of the American Brook Lamprey, Lampetra appendix, in Tennessee.
Copeia, 1982(2): 362–366.
Figure 1. Breck P, Kent (n.d). The Sea Lamprey (Petromyzon marinus). Retrieved from http://www.arkive.org/sea-lamprey/petromyzon-marinus/ on 20/04/2015
The anglerfish is referred to as one of the most bizarre looking marine species on earth, but I guess your appearance is not all that important in the dark. The deep
sea anglers generally live below depths of which sunlight is incapable of penetrating, in
the Atlantic and Antarctic oceans. There are over 200 species of anglerfish
which belong to the order Lophiiformes, the majority of deep sea anglers share a symbiotic relationship with bioluminescent bacteria. Bioluminescence, meaning ‘living light’ is generated by specialised bacteria as a result of chemical
reactions.
The female deep sea angler is equipped with an esca or ‘lure’ which is a modified dorsal fin filled with
bioluminescent bacteria. The bacteria emit light from a chemical reaction known as the luciferin luciferase reaction; it utilizes oxygen to react with the lucerifin while luciferase acts as the catalyst. The reaction is so efficient there is almost no heat lost and results in a cold glow also know as cold light. The esca is not only an attractive
device for prey but also for attracting a permanent male mate. The bacteria share a mutualistic relationship with the deep sea angler benefiting from the nutrient rich environment the
angler provides in the esca, whilst the angler benefits by having an attractive, maneuverable appendage. The evolution of this relationship is not fully understood but is thought to have originated in early
cretaceous period; in some species of angler, the bacteria are incapable of luminescence
independent of the fish, whilst being species specific (Haygood and Distel, 1993).
Figure 2.0 The luciferin luciferase reaction. T.Wilson (2014)
The distending jaw and largely expandable stomach are characteristic of the Lophiiformes order, these increase their ability to feed on a large range of prey items, as
meals can be far and in between. By visual analysis it can be depicted that
these predators are not built for speed rather an ambush approach. When an
unsuspecting meal is lured near the mouth of the angler, the female fish
inhales pulling water and the prey into its large mouth trapping it with its large
translucent teeth, the water is able to exit the fish via the gills leaving the
prey to be swallowed. The anglers rely heavily on movement detection rather
than on vision at such depths, extremely sensitive organs known as lateral lines detect movement and vibrations (Pietsch, 1972).
These creatures exhibit sexual dimorphism which is a
phenotypic difference in males and females of the same species. Male deep sea
anglers are several magnitudes smaller in comparison to the female and seem to serve one
purpose and that is to find a female and mate with her. He does this by permanently
attaching himself to her becoming a parasite using her blood supply and
nutrients. After he has attached himself enzymes are released by the males
which dissolve his organs except the testes, which supply the female with
sperm. The female can carry multiple parasitic males on herself at one time as
a method of ensuring adequate sperm supply (Pietsch, 2005). The evolutionary history of the deep sea angler is farm from understood as are many creatures that inhabit the depths of the oceans. Survival is by any means possible and the angler have certainly demonstrated that life is possible in very extreme environments.
Video with thanks to BBC Earth https://www.youtube.com/watch?v=UXl8F-eIoiM
References:
HAYGOOD, M. G. & DISTEL, D. L. 1993. Bioluminescent
symbionts of flashlight fishes and deep-sea anglerfishes form unique lineages
related to the genus Vibrio. Nature, 363, 154-156.
PIETSCH, T. W. 1972. A Review of the Monotypic Deep-Sea
Anglerfish Family Centrophrynidae: Taxonomy, Distribution and Osteology.
Copeia, 1972, 17-47.
PIETSCH, T. W. 2005. Dimorphism, parasitism, and sex
revisited: modes of reproduction among deep-sea ceratioid anglerfishes
(Teleostei: Lophiiformes). Ichthyological Research, 52, 207-236.
Figure 1.0 N.J. Marshall (2010) Deep Sea Anglerfish
(Bufoceratias wedli). Accessed 13/04/2015 from
http://australianmuseum.net.au/image/a-deepsea-anglerfish-bufoceratias-wedli
Figure 2.0 T. Wilson
(2014). The luciferin luciferase reaction. Accessed 13/04/2015 from
http://animals.howstuffworks.com/animal-facts/bioluminescence3.htm.
Nature exhibits many unsuspecting and unusual symbiotic
relationships, to which all are not beneficial to both parties. The different
symbiotic relationships include commensalism, mutualism, and parasitism.
Parasitism is the negative end of the spectrum whereby one symbiont benefits at
the cost of another. An explicit example of parasitism is the Cordyceps fungus
with various species of forest ants.
The Cordyceps fungus varies widely over the large array of
arthropods, most of which are species / host specific. Ants in particular are
especially susceptible to the fungus which is able to wipe out
entire colonies in a matter of weeks. It is estimated that approximately 8
million ants can occupy a single hectare in a forested environment; this may
partially explain why Cordyceps is more prevalent in forested locations. Currently
is it hypothesised that Cordyceps may be responsible for the population
regularity and stability in arthropod species in tropical forest environments,
for the reason that no one species gains the upper hand so to speak. Cordyceps, like most other fungi releases spores to reproduce with an array of different methods (Evans, 1982).
Figrure 1. Forest ant infected with Cordyceps fungus. Photographer: L. Austin (2003)
Once an individual ant has become infected they can start to
show symptoms, typically in the change of behavioural patterns. Their focus turn to attacking themselves, almost in
an attempt to rid their bodies of the crippling fungus. It almost seems to take control
of the ants as it forces them to head to higher ground. This is advantageous to the fungus in terms of reproductive success, dispersal and infection. The individual soon dies in
a with its mandibles tightly locked around any structure that will prevent it from falling,
after several weeks the reproductive structure of the Cordyceps erupts from the
back of the ants head growing into extraordinary arrangements. Some ant species have, by some means,
come to recognise infected individuals and will carry and dump the infected away
from the colony. Obviously this is to prevent the remainder of the colony from becoming infected (Holder and Keyhani, 2005).
There are thousands of varieties of Cordyceps to which most
specialise on a single species of arthropod. Virtually nothing can save an
individual once infected though some ants have come to recognise the symptoms
of Cordyceps and will dispose of infected individuals. This is generally advantageous and poses minimal risk to other arthropods it is species specific. However, if the same species of ant is within close proximity to the colony that is disposing of ants they may become infected.
References:
EVANS, H. 1982.
Entomogenous fungi in tropical forest ecosystems: an appraisal. Ecological Entomology, 7, 47-60.
HOLDER, D. J. & KEYHANI, N. O. 2005. Adhesion of the
entomopathogenic fungus Beauveria (Cordyceps) bassiana to substrata. Applied and environmental microbiology,
71, 5260-5266.
Figure 1. L. Austin (2003) Forest ant infected with Cordyceps fungus. https://www.utexas.edu/courses/zoo384l/sirena/species/fungi/
Video with thanks to BBC: https://www.youtube.com/watch?v=XuKjBIBBAL8
