Killary Harbour (Irish: An Caoláire Rua) is a fjord that is located in Western Ireland. This 16km-long flooded valley acts as a natural border between the Gaeltacht (Irish-speaking region) counties of Galway to the south, and Mayo to the north. Connacht’s highest mountain, Mweelrea (elevation : 814m) rises imposingly on the northern side of Killary Harbour, whereas the mountain ranges of the Twelve Bens and the Maumturks are located further to the south.Fjords (from the norse 'fjörðr', which means "where you travel across" in English) are essentially formed when glaciers retreat and allow sea water to fill the U-shaped valleys that they have left behind. The terminal moraines of glaciers tend to be at the entrance of the fjords, which means that the 'neck' is usually shallower than the main section of the fjord just behind it. In the case of Killary Fjord, once past the entrance, the base drops as deep as 45 metres. Due to the absence of extensive steep cliff walls that line the sides, some instead consider Killary Harbour to be a 'fjard', which is a glacially-formed open space of water. There is, however, at least one peer-reviewed research paper ('An Oceanographical Survey of Killary Harbour’) that takes into account the deep underwater sides of the valley, and the paper concluded that Killary Harbour is in fact Ireland's only true fjord.
Killary Harbour is a fairly narrow channel and as such, is kept relatively sheltered and protected from the occasional fury and strong currents of the North Atlantic Ocean. This not only makes it an ideal location for scuba diving, but is also one of the reasons why the area is a prime location for shellfish farming. The marine animals most known to local divers, however, are the conger eels (Conger conger). These massive eels can grow to over two metres in length and have been known to weigh over 70 kilograms, making them the largest eels in the world by weight. They are also fairly aggressive when provoked and can, albeit extremely rarely, even attack divers.
Interactive Location Map
Scubadive West is a family-run PADI 5 Star Dive Centre that is located right on the mouth of Killary Fjord. The dive centre was established back in 1992, and is currently run and operated by two brothers, Cillian and Breffni Gray. The centre offers a large range of PADI dive courses as well as dive gear rental. The full list of what the centre offers, the prices, as well as their booking and cancellation policies can be found on their website.
If you are new to diving in European waters, the first thing that might strike you as a little unusual are the orange 'blobs' that jut out of the surrounding rocks. These growths are a type of soft coral that is very common around the coasts of the North Atlantic Ocean. Some can resemble mangled fingers that seem to be reaching upwards, and as such, are quite appropriately known as dead man's fingers (Alcyonium digitatum).
Dead man's fingers are suspension feeders and filter out plankton from the water column by extending white tentacles at the ends of their feeding polyps. These tentacles, as well as those of other cnidarians like them, are embedded with stinging, which are structures that contains barbs that, upon contact, are ejected into the tissue of prey. The barbs contain an immobilizing toxin that helps to subdue the prey before they are pulled in by the tentacles for consumption. The extended tentacles dramatically transform the otherwise leathery appearance of dead man's fingers into one that is soft and furry.
Cnidarians generally have two life-cycle stages, which helps to further subdivide the phylum into its three major classes. Sea anemones and corals, like dead man's fingers, belong to the Anthozoa class. Anthozoans only have the sessile polyp stage, which means that they are not free-moving (although there are some exceptions) and are generally oriented with their mouths pointing upward. Scyphozoans, on the other hand, predominantly have the mobile medusa stage, which means that they are free-moving and are oriented with their mouths pointing downward. This class includes the well-known sea jellies, such as the compass sea jelly (Chrysaora hysoscella). [The term 'jellyfish' is a misnomer, as they are not fish. This is the same reason why it is more accurate to call starfish 'sea stars' instead]
Both the polyp and the medusa stages are present in the third major class, Hydrozoa, which includes hydras as well as other colony-forming species. The deadly Portuguese man o' war (Physalia physalis) is probably the most famous member of this class, and it differs greatly, at least physiologically, from single organisms like sea jellies. This is because it is an organism that is made up of an entire colony of distinct parts called 'zooids'. These parts have to function together as an individual organism and are so integrated and dependent on all the other parts that they would not be able to survive if separated. The of hydrozoas are also sometimes consumed by other animals as a defensive mechanism.
Colour of Anemones
Dead man's fingers are not the only common anthozoans that you will encounter in Killary Fjord. There are also various species of sea anemones that come in many different forms and a huge variety of dazzling colours. The enchanting jewel anemones (Corynactis viridis) are by far the most striking. Although the meaning of 'viridis' is green, their colonies can also be found in hues of pinkish-purple to various shades of orange and red, with the spherical tips (known as 'acrospheres') of their tentacles in a colour that oftentimes sharply contrasts the rest of the polyp. This can give the impression that the anemone is sparkling, hence the name. My dive buddy, Dan, said it best:
"The colour patterns that these amazing colonies produce across the walls, spread out around the Irish coastline, are truly dramatic and the battles between the different colonies make for the most amazing and dazzling splashes of colour, unique to the geographical location of the dive.
Fluorescent photoproteins are also present within their tissues, which makes the colouration even more spectacular under certain wavelengths of light. These photoproteins absorb both blue (short wavelengths of 400–500nm) and ultra-violet light and then re-emit the light in different fluorescent colours (longer wavelengths of 500–700nm). Fluorescence can sometimes be mistaken for bioluminescence and phosphorescence, but both of these differ in the mechanisms in which the light is emitted. Bioluminescence, for instance, releases light via chemical reactions, whereas phosphorescence is when light is first stored and then subsequently released over time. The video below highlights the orange fluorescence of a jewel anemone whilst feeding. It was shot by Coral Morphologic using a 470nm blue light.
Like the previously mentioned jellyfish and starfish, the name 'jewel anemone' is also a misnomer. Jewel anemones (Corynactis viridis) belong to the order Corallimorpharia, whose members are more closely related to corals that generate hard skeletons, known as stony or hard corals. 'True' sea anemones belong to the order Actiniaria, one of which is the snakelocks anemone (Anemonia viridis). These anemones have long snakelike tentacles that are green in colour, hence the 'viridis' name, and often with purple acrosphere tips. The tissue of their tentacles, like jewel anemones, also fluoresce under ultra-violet and blue light. These tentacles sway and undulate according to the currents and despite being retractable, like the tentacles of the other aforementioned cnidarians, are almost always extended. They also contain zooxanthellae, which are symbiotic algae that provide the anemones with nutrients. Zooxanthellae are photosynthetic organisms, however, which means that snakelocks anemones are usually found in the upper layers of the water column, where sunlight is strongest.
One creature that may not immediately be recognised as an anemone is the cloak anemone (Adamsia palliata). When small, this anemone colonises a shell that a hermit crab (Pagurus prideaux) has occupied. Over time, the crab grows and the anemone with it. But instead of switching shells when the original shell becomes too small for the hermit crab, the hermit crab simply allows the cloak anemone to take the shell's place, hence the latter's name. This symbiotic relationship benefits both parties--the hermit crab, when threatened at least, is protected by the anemone with an ejection of long sticky strands (called 'acontia') that contain stinging nematocytes; whilst the anemone benefits both from food scraps, and also uses the hermit crab as a form of locomotion, essentially hitchhiking, if you will.
There are many different modes of locomotion that are used in the animal kingdom. Echinoderms, whose members are extremely common in the waters around Killary Fjord, use tube feet to move around. These tube feet function by using hydraulic pressure that creates suction, and with the help of sticky mucus, allow them to adhere to surfaces. Subsequent waves of contractions, drawing backwards, and then relaxations of these tube feet cause the echinoderms to move slowly, but surely, along. Some echinoderms, like sea urchins, sometimes use both their tube feet and their articulated spines together to navigate tricky terrain. This also gives them the ability to roll themselves upright if ever they find themselves inverted.
Gastropods, like the candy-striped flatworm (Prostheceraeus vittatus), use a very similar mechanism as the tube feet of echinoderms, but without the hydraulic pressure. The foot (or base) of gastropods are covered with a layer of very fine cilia, that also utilises waves of contractions and relaxations. The cilia can be so fine that the gastropod may even seem to slide rather than crawl. Sticky mucus is also excreted by the foot which assists the gastropod to move. This excretion leaves a trail that not only can be followed by other individuals from their species (in a peculiar ritual appropriately called 'trailing'), but also by their predators.
Not all gastropods use cilia for locomotion, however. Royal flush sea slugs (Akera bullata), for instance, can sometimes bob up and down erratically in the water column by flapping their fleshy wings-like protrusions, which are known as 'parapodia'. These sea slugs are primitive, and have been around for the last 160 million years. They are also related to sea hares, but unlike sea hares, they swim in an upright position with their external shell facing downwards. Royal flush sea slugs occasionally form large swarms that swim (or bob around) together, but if you do happen to encounter one of these swarms, be sure to not agitate them... if not, you just might find yourself covered in purple ink!