Water world

A few winters ago, I spent a week in one of the smaller islands of the Andaman archipelago. Some mornings I could walk most of the way around the island, at the edge where land and sea meet. The green wall of trees on one side would loom over the mysterious blue depths on the other. Our world is a water world; almost three quarters of its surface is ocean, over half the life on earth is oceanic. What do we know about it?

A recent read (partly hidden behind a paywall) overturned everything that I though I knew about the earth. It seems that plants make up less than 10% of the biomass of the oceans (they make up 95% of the biomass on land). The waters of our world are dominated by animals, bacteria, and complex single-celled creatures collectively called protists. These three groups make up 80% of the biomass of the oceans (on land, these groups make up 2% of the biomass). In the oceans fast growing primary producers make up about 15% of the biomass, whereas consumers, with a slow lifecycle, make up the rest. There are two different worlds sharing this planet of ours!

Green jewel bugs

If you are the kind of person who looks closely at leaves and trees now and then, it won’t be long before you start seeing the aptly named green jewel bug everywhere. It is widely spread across continental Asia. I see it in gardens all the time. So I was not going to post the featured photo.

But there is something interesting about these true bugs: apparently they are not found in the islands of Indonesia, Philippines, Sri Lanka and Japan. The photo you see above was taken in South Andaman near the Mount Harriet National Park. I wanted to put on record the fact that there are islands where it can now be seen. Whether it flew or was carried there by winds, or was introduced inadvertently by humans is unclear. Interestingly, the upper parts of its legs are orange, whereas the ones I’ve seen before all had green or black legs. There seems to be quite a bit of variation in form, size, and colour in this species, so I’m not sure how significant this colouration is.

It is fairly easy to photograph these, and other, metallic shield bugs. They are easily seen on upper surfaces of leaves, branches and flowers. They do not hide the moment they spot the huge eye of a camera looking at them. Maybe this has something to do with the fact that they can release bad-smelling chemicals when attacked, and therefore are not good things for predators to eat.

Note added in October 2020: Perhaps I was mistaken in the identification. This looks smaller than C. Stollii, and has somewhat different markings. Could it be the Chrysocoris patricius? I’m not yet sure, and I must read more.

Leaving Andamans

A relaxed holiday ended roughly as it began: with the chaos of a ferry. A queue of people moved slowly up a gangplank to the ferry, where the harbour master and a ship’s officer checked tickets. Before that there were two people loading luggage. We presented them ours, and it seemed to be passed into a hold. Later we found that it was piled up in the main cabin.

seawageairvent

An interesting thing about sea-going vessels is that everything is labelled. When you think about it you realize that on board an airplane also everything is labelled, but much of the labelling is in the area and equipment handled by crew. The largest space in a plane is passenger seating, and the labelling there is discreet. On the ferry we did not sit in the cabin, but preferred to go up to the deck. It took me a second to figure out what the "Sea Wage Air Vent" is (see photo above).

View of Sitapur beach from ferry, Neil Island, Andaman

We looked at Neil Island as we pulled away. The jetty and buoy which marked the scuba diving point fell away. We had our last view of Lakshmanpur beach (above), and then the whole island could be encompassed in one view (featured photo). The sea was wonderfully clear, and our wake had lovely blue tones in it. Someone excitedly pointed out a dolphin. We looked for one, and talked lazily about dugongs and sea turtles which we had missed. An hour later we were in Port Blair, and on our way to the airport. The year and the holiday were about to end.

Patterns from turbulence

Walking along a beach before sunrise I saw a piece of brain coral had washed up at night. I have no idea what are the uses of the intricate patterns on the coral. The valleys between the ridges are where the feeding tentacles of the coral rest when they are not waving around. But why is are the ridges so complicated in shape? I had no clue about this. But I thought I should be able to understand the pattern in the sand around the piece of coral.

Small scale turbulence in water runoff on a beach

As the tide recedes, waves break near the shore, and the water runs up the sand. Then, the water drains back. As you can see in the photo above, the water breaks into little eddies as it drains, and the eddies conjure up the pattern in the sand around the piece of coral. You can see a pattern of parallel grooves.

The spacing between them is determined by the viscosity of water. It turn out that if the water tries to drain away with a speed of about a meter per second, then turbulent eddies of size of about 5 millimeters should be seen. That size is about the smallest scale that you can see in the pattern. Interestingly, this gives us a way to see how fast the water drained away after the water has gone. Look at the smallest structure in the pattern left by the water, and the speed should be inversely proportional to this. This means that the finer the pattern, the faster the water drained!

This is all about very small scale patterns. There is much more to the formation of patterns in the sand, as another blog discusses. As I walked about, the horizon began dipping towards the sun, and I was distracted by the easier pattern of the daily sunrise.

A restful beach

One of the most restful beaches I found in Andaman was the beach in Neil Kendra. I was biased of course; a cut on my leg prevented me from entering the water, so I was a beach comber during my vacation. The Neil Kendra beach had no people at all. It is not a swimming beach, because it is fronted by corals and mangroves.

I did not pay much attention to mangroves before 2004. Then when extensive reports came in of how mangrove ecosystems saved villages from the tsunami, I began to find more information on these swampy backwaters of Mumbai. Today it seems to be an integral part of coast management, given that it not only protects the shore, but actually builds new area. Also, the coastal ecosystem around mangroves is extremely productive, since it harbours many kinds of fish.

Mangroves in Neil Kendra, Andaman

None of this was on my mind as I walked on the beach. My indoors job leaves me little time to walk in the sun. So I was making the best use of my vacation to soak in the vitamin D as I tried to work up an appetite for lunch. The Family thought I was mad to walk in the heat; she sat in the restaurant and sipped a lime and soda. The roots of these trees formed beautiful traps which reflected in the pools of water below them. They gave me some nice photos even in the noonday sun.

Mangroves are like the kindergarten, seagrasses are the secondary schools, and coral reefs are the high schools and colleges for fishes! And, once [the fishes] graduate from university, they return to kindergarten to spawn! -Khun Pisit, cofounder of Thailand’s Yad Fon mangrove preservation project

I’m used to the mangroves of Mumbai. I’ve seen fisherfolk walk among them at low tide laying pots to trap shrimps, or harvesting previously laid traps. I’ve spent weekends near these mangrove swamps birdwatching. These are very popular with birdwatchers around Mumbai. The very fact that so many wading birds can be seen in such places means that there are fish and crustaceans here. In Mumbai one cannot be oblivious of the fact that builders constantly try to have laws and regulations changed so that they can build over these swamps.

Still, with India’s huge coastline, I’d expected that India would be among the top ten nations harbouring mangroves. It was a shock that it isn’t. Even more shocking is the fact that the Indian Forest Service reports that Kerala had 6 sq Km of mangroves in 2013! Only Odisha, West Bengal and Andaman have dense mangrove forests. Indonesia has more than twenty times as much of mangrove forests as India does. I guess if we bring up our children to eat fish, we should do a little more for mangroves.

Barnacles, limpets or gribbles?

The Leafless walked in from a walk by the beach to tell us about a log which had washed in. She said it was full of shells. I thought it might be barnacles. I finished my tea and walked out to look at the log.

It was a freshly broken branch of a tree, and it had been colonized by bivalves. Clearly these were not barnacles or limpets. Were they gribbles? I didn’t think they were. They could be piddocks; those are bivalves. But the piddock shells I got to see in a few days did not look like these. I wonder what these mysterious creatures are. Look at the movement of the shells on the extreme left in the 7th second of the video below: they look like real bivalves.

I wonder if anyone can help me figure out what they are.

How to spot a carnivore

If you walk along the beach and find a group of people clustered around something that has washed up, hotly discussing whether it is a lobster, you would be sure you had fallen in with a bunch of confirmed carnivores.

The Leafless and The Family stopped at this head as I was taking photos elsewhere on the beach. I realized they must have come on something interesting, so I walked over. The Family thought it was some kind of a lobster. The Leafless asked "Wouldn’t it have claws?". I agreed with both, but it was a bit of a mystery, as we all took photos of this beautiful head.

Spiny lobsters, also known as langouste or rock lobsters, are a family (Palinuridae) of about 60 species of achelate crustaceans, in the Decapoda Reptantia. -Wikipedia

A little research cleared this up. Technically we’d seen the head of a spiny lobster. I think I’ve eaten them in France. I’m certain that The Family and I have walked around farmer’s markets where there were Langoustes on sale. Energized by this sight we order a lobster for dinner. It wasn’t available, so we settled for crabs instead. If you see a crustacean with a long spiny antenna and small or non-existent claws, it is almost certainly a spiny lobster.

Fish in a tide pool

On arrival at Neil Island we met a young auto driver called Suman. He turned out to be very articulate, and had a very pleasant way of explaining to us when we disagreed on anything: including fares. There were many pleasant auto drivers on the island, but of those we met he was the most articulate. Once we were at a loose end in Bharatpur beach, when we met him.sitapurrocks He asked where we wanted to go, and we said that we would go to whichever place he wanted to show us. He took us to Sitapur beach.

That was the first time we saw this beach, with its spectacular crescent of yellow sand, and the wonderful submerged layers of rocks. You can see the clarity of the water in the photo above. I think the rocks must have been heaved up in the 2004 earthquake. I loved the very eroded flat slabs of rock, some with holes bored by piddocks.

Rocks around Sitapur beach, Neil Island, Andaman

The tide was out, and we walked out over the bare rocks to peer into little tide pools. Some of them had tiny fish which would dart away as soon as they saw something looming above the water. Eventually I captured the featured photo by crouching low on a rock until the fish came to rest. Until I saw the photo, I hadn’t noticed the bubbles at the tips of the fronds of seaweed.

The beach was empty except for us and a French couple swimming in a deep pool among the rocks. We walked up to a distant rock fall and came back. Suman was waiting expectantly, and his face lit up when we answered his unasked question by saying this was a beautiful spot.

Eating in or eating out?

The little islands of Ritchie’s archipelago have small populations by Indian standards. Neil Island has a permanent population of about 3000, with about that many more tourists in peak season. A large fraction of the population runs restaurants. Signs such as the one in the featured photo were common. We also read one which promised "North and South Indian, Bengali, Continental, Chinese, Israeli and Bhutanese food". I had looked at these signs as indicators of where most visitors came from, but the reference to Bhutanese was a jolt. It is unlikely that there are many Bhutanese tourists here. Perhaps it is a nod to the fact that momos are popular all across the northern part of the country.

Typical beach eatery in Neil Island, Andaman

On our first day in the island, we came across this little stall on the beach. While we had a tea, the man told us about what he could get us for dinner. His recommendation was lobsters, and the price he offered was good. He insisted that The Family take down his phone number. If we ordered he would deliver the dish to our room in the hotel. Unfortunately, we never got around to ordering. There are too many walk-in options. What sea food we ate on the island was wonderfully fresh.

Reading on the beach

There were lots of animals on beaches and in the sea around Neil Island, but Lepus timidus were not among them. So the sign in the featured photo had to be in error. Also, as one of my nieces pointed out, the buoy is too big for any known hare. We saw many interesting signs on Bharatpur beach, but this probably takes the award for the zaniest mistake.

Glass-bottomed boats, Neil Island, Andaman

You can take glass-bottomed boats out of Bharatpur beach to see corals. Since the cut on my leg prevented me from getting into the water, I took this more distant view of the sea bottom. The boats had terrific names; two of the best are in the photo above. I liked “O. B. Sea Prasad”, whose subtext every Indian will instantly follow. A gloss for others: affirmative action in India is mainly based on castes, and OBC stands for Other Backward Castes. This boat was probably bought using an affirmative action bank-loan. The name of the boat standing next to it is a really zany take on Santa Cruz. There may have been an effort at a pun: Santa Cruise, but it didn’t come out very well.

I loved reading on the beach.