Parasitic Lampreys

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 post metamorphosed 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

Bioluminescent Bacteria and the Deep Sea Anglerfish

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.

Figure 1.0 Deep Sea Anglerfish (Bufoceratias wedli). Photographer: N.J. Marshall (2010)

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.

A Tad Bit Antsy

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