A quick perusal of images available online shows that yes indeed, lots of stuff is attached to and growing on whales. Most of what I see are barnacles. In my quick assessment it appears that grey whales are the winners of the ‘how many barnacles can you fit’, contest.
Wait a second, is it grey whales or gray whales? Whichever. Their binomial name is Eschrichtius robustus. No matter the name, and they do go by several, include the California Gray Whale, Pacific Gray Whale, and Gray Back Whale, this is a subject I just had to look into a bit more.
It turns out that our friend Charles Darwin mentioned barnacles that live on whales. If you are not in the know, Darwin wrote a monograph on barnacles in 1854, before his more famous, On the Origin of species by means of natural selection: Or the preservation of favoured races in the struggle for life, which was published in 1859. Darwin identified a number of species, and genera, that were observed on whales. Here is a brief list of notes from that publication.
Genus Coronula.
“Geographical Distribution.—The genus is found wherever whales occur, … It is asserted that sometimes as many as a couple of hundred specimens will adhere to a single whale.”
Coronula balaenaris. Attached to whales in the Southern Ocean.
Coronula diadema. Habitat, attached to whales, in the Arctic Seas; United States and Great Britain, Atlantic Ocean, including the Gulf-Stream. Darwin also includes New Zealand but this listing is followed by a question mark. That kind of note is near and dear to my heart, my notes are filled with questions marks. However, sometimes I’m not certain I remember why I put the mark there, was I uncertain of the information or did I want to study this question more. In Darwin’s case I think it means he has some information regarding whales from New Zealand that house this species of barnacle, but the information is suspect or incomplete in some way.,
Coronula reginae. Habitat, attached to whales, Pacific Ocean.
Genus Tubicinella.
Habitat, Southern Pacific Ocean, Western South America, New South Wales, Cape of Good Hope; imbedded on whales, and often associated with Coronula baaenaris.
I’m a little shocked that the species of whale was not listed. Does this mean they live on many species of whale? This whole idea of barnacles living on whales begs even more questions, How many barnacles species are commonly found on whales? Will any whale do? Are there barnacle species that are only found on whales? Are there barnacle species that only latch on to a specific whale species? Can barnacles species, not usually found on whales, still latch on to whales? How many barnacles can fit on a whale? Do barnacles slow whales down? Some of the answers to these questions will overlap each other.
I better stop there with the questions and get to attempting to answer them or this essay will be much longer than I want. Let’s take a stab at answering these questions:
How many barnacles species are common on whales?
Darwin lists three specific species, all from one genus Coronula, and a second genus, Tubicenella, that were observed on whales. The “whale barnacle” genus, Coronula, contains only two species Coronula diadema and C. reginae. The species Darwin listed as Coronula balaenaris is now considered Cetopirus complanatus. Besides these three an additional five species Crytolepa rhachianecti, Tubicinella major, Conchoderma auritum, Conchoderma virgatum, and Xenobalanus globicipitis.
Will any whale do?
With just Darwin as a resources, I suspect yes. If you are a barnacle that latches on to whales, then any whale will do (with some limits). I come to this conclusion based on Darwin not identifying specific whale species and some of his statements, for example “The genus is found wherever whales occur”, and the general “…imbedded on whales”. More recent work lets us tease out more specifics. Some whale riding barnacles have been observed on several species of whale. While others are known from just a specific species (more on this below).
Are these barnacle species only found on whales?
The family Coronulidae are known as the whale barnacles. Darwin mentions members of this family, Genus Coronula. With that moniker “whale barnacles” they must only be found on whales, right? Well maybe not. Though whales may be their preferred habitat, some barnacles found primarily on whales, can be found on sea turtles, and perhaps any big-ass creature that has a good landing area. But at least one species, Xenobalanus globicipitis, is referred to as an obligate cetacean barnacle, meaning it survives only on whales.
FYI Xenobalanus globicipitis is a stalk barnacle, I couldn’t resist a quick outline drawing of this species.
Yes, again with reservations (that is they might find another species but they also might not thrive on that species). Species specific barnacles include Crytolepas rhachianecti, Cetopirus complanatus, and Tubicinella major. These have only been found on specific whale species. Crytolepas rhachianecti have only been observed on the Gray Whale, while Cetopirus complanatus have only observed on the Right Whale, Eubalaena glacialis, and then only in the Southern Hemisphere. Tubicinella major have also only been observed on right whales, and again in the Southern Hemisphere with sketchy reports from the North Atlantic.
Can barnacles species, not usually found on whales, still latch on to whale?
I expect the answer to this is yes, but they wouldn’t survive for long. I cannot find specifics. A common barnacle on East Coast rocky shorelines Semibalanus balanoides, is found not only on the rocks, but wooden docks, pilings, crab carapaces, boat hulls and a host of other hard substrates. Is whale skin hard/non flexible enough to allow successful housing of a regularly hard-rock barnacle? Whale barnacles imbed themselves within the whale’s skin. Which makes some sense, because if they are sloughed off they are likely doomed to floating into the depths of the ocean and being swallowed by the Kraken (well, maybe by a fish). So a barnacles without the ability to imbed would need a hardened base, like the other barnacles already imbedded. As we have read some species do that. Failing that, I think “regular” barnacles would fall off too easily.
How many barnacles can fit on a whale?
Darwin mentions that a “couple of hundred” might be found on a whale. Other sources don’t mention the number but instead the weight of the barnacles carried. Some web resources state several hundred pounds to 1000 lbs. Just the fact that these use pounds and not kilograms makes me suspect the source. Some hard numbers, from the Kane et al. paper below, mentions up to 286 individuals on an Orca. Hard numbers are hard to come by but I suspect Gray Whales, which are heavily infested, beat that number easily.
Do barnacles slow whales down?
Probably. Though Wikipedia states this relationship is commensal, that is the barnacles benefits but the whales is not harmed. I call bogus on that answer. Even if whales are only slowed a little, that means they use more energy to move, which means less energy for everything else.
Who benefits?
Barnacles filter feed so are catching food as the whale moves. Baleen whales aim for food, something like krill, which in turn, is feeding on smaller plankton. This is what the barnacles are after. Toothed whales, though barnacles are more common on baleen whales, scatter bits of prey. Thus, overall the barnacles benefit, and the whales are likely hampered. This relationship, then, is considered parasitic.
Are there other odd aspects to this whole barnacles on whales thing?
One of these barnacles, Conchoderma virgatum, latches on to a copepod parasite, that in turn had latched on to the whale. The other barnacle, listed herein, from this genus Conchoderma auritum, is usually found latched onto other barnacles, which, in turn, you guessed it, had latched on to the whale.
Barnacles latch on to barnacles, that latched on to whales. Yes, you read that right.
A bevy of barnacles inhabit, and perhaps inhibit, whales. Now the big question, why? Of course why questions are evolutionary questions. Any ideas?
Sources and further reading
Carrillo JM, Overstreet RM, Raga JA, Aznar FJ. 2015. Living on the edge: settlement patterns by the symbiotic barnacle Xenobalanus globicipitis on small cetaceans. PLOS ONE. 10 (6): e0127367.
Chan BKK. 2012. Coronulidae. WoRMS. World Register of Marine Species.
Darwin C. 1854. A monograph on the sub-class Cirripedia, with figures of all the species. The Ray Society. pp. 153–154.
Hayashi R, Chan BKK, Simon-Blecher N, Watanabe H, Guy-Haim T, Yonezawa T, Lvy Y, Shuto T, Achituv Y. 2013. Phylogenetic position and evolutionary history of the turtle and whale barnacles (Cirripedia: Balanomorpha: Coronuloidea). Molecular Phylogenetics and Evolutiuon 67: 9–14.
Hermosilla C, Silva L, Prieto R, Kleinertz S, Taubert A, Silva M. 2015. Endo- and ectoparasites of large whales (Cetartiodactyla: Balaenopteridae, Physeteridae): Overcoming difficulties in obtaining appropriate samples by non- and minimally-invasive methods. International Journal for Parasitology: Parasites and Wildlife. 4.
Hermosilla C, Silva L, Kleinertz S, Prieto R, Silva M, and Taubert A. 2015. Endoparasite survey of free-swimming baleen whales (Balaenoptera musculus, B. physalus, B. borealis) and sperm whales (Physeter macrocephalus) using non/minimally invasive methods. Parasitology Research. 115.
Kane, Emily A. and Olson, Paula A. and Gerrodette, Tim and Fiedler, Paul C. 2008. Prevalence of the commensal barnacleXenobalanus globicipitis on cetacean species in the eastern tropical Pacific Ocean, and a review of global occurrence. Fishery Bulletin, 106(4), pp. 395-404.
Pastorina G, and Griffin M. 1996. An extant whale barnacle (Cirripedia, Coronulidae) from Holocene deposits of Buenos Aieres (Argentina). Crustaceana 69: 769–770.
Scarff JE. 1986. Occurrence of the barnacles Coronula diadema, C. reginae and Cetopirus complanatus (Cirripedia) on right whales. The Scientific Reports of the Whales Research Institute: 131–134.