Saturday, July 31, 2010

Barking Crab - Experience, Observations and Research


The third day began with a brief discussion about the tide levels. We were able to identify that it was a low tide to begin with around 10am. It was at almost a 3ft - 4 ft level which indicated that it was probably the lowest as per the prior year tide charts listed on at about 10.15 am, we walked to the shoreline (spot 1) in order to observe the marine life present on the walls (mainly in the inter-tidal zone) and visible in the water. The clarity of the water on a scale of 1-10 (10 being the clearest) was of about 5 as per me.

After, we observed some of the different plants and animals present on the shoreline, we continued on our way to the Barking Crab docks. We stopped near the East India towers (spot 2) to check the water for any crabs or other animals present. After noting the observations we walked down to the barking crab. On our way we also encountered a man from National Oceanic and Atmospheric Administration (NOAA) who was measuring the tide levels. He notified us that the tide was still low and the high tide was coming in.

As we reached the barking crab, we went down to its docks (spot 3) in order to observe the marine life present. The docks were the habitat for various different sub-tidal plants and animals. It seemed like the life was centered as colonies hanging under the docks in small lumps denoting the presence of a small webbed ecosystem. We formed our hypothesis about our observations in groups later and then researched in order to test our hypothesis by identifying the different plants and animals we saw.

Spot 1 Observations, Hypotheses, and Research:

Inter-Tidal Zone

1) Thin Branched, Blackish Brown, Fibrous, Leafy, Bushy Weed - It was hanging of the walls in the inter-tidal zone and was also present in the sub-tidal waters. It looked like a species of black sea weed.

This seems to be like Gulf weed which is bushy, has narrow blades with toothed edges. It is golden brown in color when fresh and turns dark brown on drying. It has free floating species as well as attached species, just like the ones I observed in the water and on the walls.

However, the weed may be a variety of rockweeds that are found in the upper inter-tidal zones as due the long receptacles and slender shape of the blades.

2) White Small Group of shells - There were white shells of Barnacles clustered around the green and the black weed. Some seemed to be in groups of 4 to 5. They had little black dots in the center of the white shells. the approx. length of the cluster of 4 barnacles was about an inch.

It seems like this species of barnacles is the 'down-under' barnacle as I noticed that there were a few groups of four shells present. Also, I saw them in the inter-tidal zone and it is a high possibility that these barnacles were the 'down-under' barnacles rather than the native northern rock barnacles which mostly survive in the sub-tidal zones. However, it could be a little gray barnacle which also exists in clusters in the inter-tidal zone.

Spot 2 Observations, Hypotheses and Research:

1) Small shiny silver fish, worm-like, black stripes along body - They are called shiners. There were almost 20 - 30 fish swimming in the water. They were almost 2 inches in length.

These are the tiny herring fry fishes that are common in sub-tidal areas. They can survive in turbidity and low-oxygen areas. They feed on algae, zoo-plankton, and small insects.

Spot 3 Observations, Hypotheses, and Research:

Barking Crab - Inter-Tidal Zone

1) Green, broad, leafy, smooth textured, weed - This was like a broad leaf like weed which was stuck under the dock with the various other plants and animals. It resembled the lotus leaf, and it was very thin and soft like a tissue paper. It was 5 - 5.5 inches in length.

This seems to resemble a sea lettuce which is common in brackish shallow sea waters. It is thin and has a waxy surface. However, its lenght of 5.5 feet seems to be more than the avg length of the sea lettuce. Hence, it may not be a sea lettuce but monostroma species.

2) Brown, Branched, Root-like, clustered weed - This weed was a complex cluster of branches just like a fibrous root. It had hairy branches which entangles into each other and it was soft. It was almost 4 inches in length.

This seems to resemble the slippery tangle weed as because of it soft, fine branches and also the bushy nature. However, it may be a brown slime weed which is slender and stringy, coarsely branched and also has a soft texture.

3) Black - Brown, branched, leaf-like, stemmed weed - This weed was approximately 2.3 - 2.5 inches long and it had projections coming out of the stemmed branches. It was soft as well and it popped like a bubble wrap on pressing.

This is also most likely a form of rock weed. It resembles F. vesiculosus which is the most common and widespread rock weed species. It pops like a bubble wrap as due to the air bladders placed at intervals within the blade of the weed.

4) Hard, Black Colored, Slimy, Shell - This seemed like a large dead mussel's shell. It has fine white line designs on the top on a black color. It was 1 inch wide, 2 inches tall and almost 1/2 inch thick. It also seemed to have a yellow flower like plant/animal on the top of it.

This mussel most closely resembles a horse mussel. It has a few pointed terminal beaks and has a blackish smooth finish on the outside shell. It has whitish tinged lines. However, it may be a blue mussel due to its color and smaller size. Also, the horse mussel is mostly found in the deeper sub-tidal waters in comparison to the blue mussel which is found in brackish estuaries as well as in deep waters.

5) Black, Worm like, multiple legged, amphi-pod - This amphi-pod was almost 1/2 of an inch in length and it seemed to survive on the mussel. It had a shape of a shrimp as it was curled and had many legs like of a centipede. There were numerous shrimps present in the mussel.

This shrimp looks like a big-eyed amphi-pod. It has large eyes and is a planktonic species. It most likely is the H. Medusarum as due to the hairy gnathopods. It also resembles the planktonic amphi-pods. However, due to it not having a long brushlike antenna, it may not fall under the category.

6) Brown, String-like, Long-bodied amphi-pod - This animal was found on one of the sea weeds seemed to be like a leg of a spider. It curled up and rotated. It had a string like very slim body with a length of almost an inch. It resembled like a fibre and had tiny projections near the head. It thought it was some kind of a sea spider or related to the family of worms. Its movement was in a curled roll-over fashion.


This is a kind of a skeleton shrimp with a segmented body. It has its head in the first thoracic segment, followed by claws and limbs in the second and third segments of its body. The roll-over movement is slow and methodical. Also the size is suitable for the classification. They generally feed on weeds , hydriods etc. and can exhibit red or brown color to match their surroundings.

7) Orange, Daisy Flower-like, squishy, tiny, spongy, material - This was a flower like plant or animal that was found on the top of one of the mussels. It was smaller than 1/4 of an inch and kind of resembled a mould to me. It seemed to belong to the fungi kingdom. There was a colony of them and they had anchored themselves to the mussels.

This orange daisy like flower like organisms belong the the Ascidiacea class or more commonly termed a tunicates. Many of these animals attach themselves to the substratum and many are immobile. These orange ones have very close resemblance to the Golden Star Tunicates. It seems like these tunicates just started their lives as they are in the form of patches. After maturing, they take forms of rolls or lobes. They are generally found as colonies in subtidal and intertidal zones. It is very common to find them around the Boston area. It may be possible that these species came from Europe on ship bottoms.

I conclude my day's bog at this stage and I look forward to our experience on the island tomorrow.

Akshat Jain

External References:
2) Peterson Field Guides - A field guide to Atlantic Shore fishes

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