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The Humble Barnacle

The Humble Barnacle

Anjana Manjunath saw goose barnacles on a Goan beach, which had entrusted their survival to a plastic bottle to which they had attached themselves and ponders the fate of marine life, now at the mercy of humans.

Barnacles are tiny, mysterious, ingenious and baffling organisms. They are extremely hardy too. Photo: Anjana Manjunath.

When John Gerard, a British botanist, proudly wrote about trees that bear geese in 1597, he was describing what he saw as a shell containing a bird. So monumental was this piece of observation that even the Royal Society of London published his findings.

Many of these shells I brought with me to London, which after I had opened, I found in them living things without form or shape; in others, which were nearer come to ripeness, I found living things that were very naked, in shape like a bird: in others, the birds covered with a soft downe, the shell half open, and the birds ready to fall out, which, no doubt, were the fowles called barnakles” explained Gerard, confidently but erroneously. Since the phenomenon of bird migration was less clearly understood then, a goose was claimed to grow in a shell as explanation for why the bird was never seen to nest in Europe.

Able to survive in surprisingly polluted and degraded environments, they can be seen here attached to a carelessly discarded plastic bottle. Photo: Anjana Manjunath.


Last week on the warm sands of Sinquerim beach in Goa, I stumbled upon a plastic bottle covered with goose barnacles (also commonly known as stalked barnacles or gooseneck barnacles and scientifically grouped under the order Pedunculata) – the same species that beguiled Gerard. It is believed to be one of the oldest surviving species.

A goose barnacle is a crustacean (not to be confused with barnacle goose – the bird!), belonging to the same family as the shrimp, crab and lobster. Notorious for its proliferation, goose barnacles are found clinging onto any flotsam, rocks and even shells of other animals. Sessile invertebrates, barnacles permanently attach themselves to firm objects in the larval stage and later form a hard outer calcite shell – its skeleton forming outside the body. Most species of barnacles have both male and female reproductive organs (hermaphroditic) but fertilisation is usually completed by another barnacle (cross-fertilisation).

At first glance, a goose barnacle appears covert with brown protracting claws that move in and out of its shell. These modified limbs or cirri allow the barnacle to feed. A filter feeder, it consumes particles suspended in water and does not endanger the diet of other animals. Its cirri reach out of the shell to strain food particles.

Enthralled by the sight of a sea animal flourishing on a plastic bottle, I carefully observed the delicate, rhythmic motion of the live goose barnacles, its brown extensions dancing to the sound of the waves in the near background. The shell of the barnacle comprises a number of hard layers with “feathery” appendages used to suck water into the shell. It’s not surprising that Gerard confused the barnacle’s smarmy body to that of a bird!

A local Goan walking by on the beach paused to point out that the goose barnacle is a local Goan delicacy, generally referred to as Konge (in Konkani) or Percebes (in Portuguese). It is the only edible species known to be relished in Spain and Portugal as well. Gopalkrishna Bhobe in his Marathi book ‘Mase ani mi’ [Fish and Me], vividly described mackerels, also from the Sinquerim beach area, as delicious. Bhobe was also a voracious contributor to Goan ethnoichthyology, examining the interaction of humans andfish. I, too, find it interesting to try and understand the impact of human activity on barnacles and other species.

A zoomed out view of hundreds of barnacles (tiny white dots) using rocks as substrata on a shore in Goa. Photo: Naresh Shirodkar.


The importance of fish varies across different communities. Fishermen depend on their knowledge of fish. Dr. Nandkumar Kamat (Faculty, Goa University) explained that “Goa is home to about 200 species of marine and estuarine fish, 60 species of crabs and a dozen species of oysters, clams, bivalves and mussels, but the actual diversity of fish and shellfish is neglected”. In recent decades, human activities have impacted marine diversity drastically. Dr. Mahesh Zingde when speaking about the impact of human-induced alteration on marine ecology of India, clearly states that the laws exist but insufficient enforcement has degraded the ocean. The abundant presence of tar balls (oil-slick from ships and containers) is one visible example of poor enforcement in Indian waters. www.irtces.com

The National Institute of Oceanography recognises three major human-induced threats to aquatic ecosystems – increase in release of CO2 which can have an adverse effect on fertility, metabolism and the survival of organisms, high nutrition input that has been abnormally increasing the growth of plant and algae, and slower exchange of oxygen that is creating hypoxic zones in coastal areas. These combined threats impair water quality and biodiversity.

In the face of such toxic impact, barnacles, interestingly, are known to survive even in polluted waters. The plates in their shells allow them to control the influx of water – an ingenious adaptation to a human altered environment. Amazingly, these barnacles chose to occupy a plastic bottle to which they are now permanently attached. Perhaps barnacles are the only wild species that can be trusted to thrive in Goa, which is now home to about a hundred polluting industries and thousands of garbage-spewing visitors.

When the sea foam suddenly engulfed the plastic bottle and carried away the barnacles into a blue abyss, I was reminded of the ebb and flow of the sea. The profusion of barnacles is to regeneration what the plastic bottle is to gross human apathy.

We often assume that the ocean is a bottomless pit that can absorb any amount of chemicals and waste; even agricultural runoff, a non-point source that is a seriously toxic pollutant. However, each waterbody has a Water Assimilative Capacity (WAC) which is the amount of pollutants that it can absorb before its natural properties alter. Fortunately, for us so far, each waterbody has an inherent cleansing system, but this system is being over-burdened and that could leave us with irreversibly damaged ecosystems. Not a cheerful thought.

First appeared in: Sanctuary Asia, Vol. XXXIV No. 4, August 2014.


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