Tag Archives: sea creatures

Friday Fellow: Blue Coral

by Piter Kehoma Boll

Sorry, guys! It has been about three weeks since my last post, but I was too busy with a lot of personal and academic stuff and wasn’t able to dedicate any time to the blog, but I’m back!

Let’s return with a marine animal as today’s Friday Fellow, the called blue coral, Heliopora coerulea.

heliopora_coerulea2c_koh_phangan

A colony of the blue coral in Thailand. Credits to Chaloklum Diving.*

Found in tropical waters of the Pacific and Indian oceans, the blue coral is a peculiar species, being the only one in the genus Heliopora and in the family Helioporidae. It is the only species in the subclass Octocorallia that has a massive skeleton, a feature more common in the stony corals of the subclass Hexacorallia. As a result, the ecological role of the blue coral is usually closer to that of stony corals that to that of its closer relatives.

The skeleton of the blue coral is composed of aragonite and has a distinctive bluish-gray color caused by the presence of iron salts. There are fossils of bluish corals with the same morphology that date back to the Cretaceous, indicating that this is a very old species.

450px-blue_coral_-_heliopora_coerulea

A skeleton of the blue coral in the Natural History Museum, London. Photo by Wikimedia user Kinkreet.**

Although widespread, the blue coral is currently considered a vulnerable species, with some population showing very low genetic diversity. This species is threatened mainly by the jewelry and aquarium trades and by the acidification of the oceans.

– – –

Like us on Facebook!

Follow us on Twitter!

– – –

References:

Babcock, R. (1990) Reproduction and development of the blue coral Heliopora coerulea (Alcyonaria: Coenothecalia)Marine Biology 104: 475–481.

EOL: Encyclopedia of Life. Heliopora coerulea. Available at < http://eol.org/pages/1006937/overview >. Access on May 14, 2018.

Wikipedia. Heliopora coerulea. Available at < https://en.wikipedia.org/wiki/Blue_coral >. Access on May 14, 2018.

Yasuda, N.; Taquet, C.; Nagai, S.; Fortes, M.; Fan, T.-Y.; Phongsuwan, N.; Nadaoka, K. (2014) Genetic structure and cryptic speciation in the threatened reef-building coral Heliopora coerulea along Kuroshio Current. Bulletin of Marine Science 90(1): 233–255. https://doi.org/10.5343/bms.2012.1105

– – –

*Creative Commons License
This work is licensed under a Creative Commons Attribution 3.0 Unported License.

**Creative Commons License
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

Advertisements

Leave a comment

Filed under cnidarians, Friday Fellow, Zoology

Friday Fellow: Savigny’s Brittle Star

by Piter Kehoma Boll

It is time to present the second echinoderm here, and for that I have chosen a brittle star, actually the most widespread brittlestar in the world. Known scientifically as Ophiactis savigny and populary as Savigny’s brittle star or simply little brittle star, this species occurs in tropical and subtropical waters of all the world’s oceans.

Ophiactis_savignyi

One tiny specimen of Ophiactis savignyi. Photo by Ria Tan.*

The Savigny’s brittle star is very small, having a disc measuring between 0.5 and 11 mm in diameter and usually six long segmented arms. It can live from the intertidal zone to about 500 meters below the surface and is often found living inside sponges in a possible commensal association, sometimes occurring in very high densities.

The reproduction of the Savigny’s brittle star can be sexual or asexual. During sexual reproduction, both males and females release gametes into the water, where they are fertilized, while asexual reproduction occurs by fission of the discs, literally splitting the animal in half and then each half regenerates the missing parts. Males seem to be more prone to engage in asexual reproduction, which leads to a higher rate of males in the population in relation to females.

Ophiactis_savignyi2

Hundreds of arms of many individuals of Ophiactis savignyi poking out from a spong Spheciospongia cf. vagabunda. Photo by Ria Tan.**

The diet of the Savigny’s brittle star is composed mainly of detrites or dead animals. Its association with sponges may be related to the fact that sponges pump water that carries particles that may also serve as food for the brittle stars. It is common to found the cavities of certain sponges completely filled by individuals of the brittle star, some of them already too large to be able to leave the sponge.

– – –

Like us on Facebook!

Follow us on Twitter!

– – –

References:

McGovern, T. M. (2002) Sex-ratio bias and clonal reproduction in the brittle star Ophiactis savignyEvolution 56(3): 511-517. https://doi.org/10.1554/0014-3820(2002)056[0511:SRBACR]2.0.CO;2

Wikipedia. Ophiactis savigny. Available at < https://en.wikipedia.org/wiki/Ophiactis_savignyi >. Access on March 22, 2018.

– – –

*Creative Commons License
This work is licensed under a Creative Commons Attribution-Share Alike 2.0 Generic License.

**Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommerical-NoDerivs 2.0 Generic License.

Leave a comment

Filed under Echinoderms, Friday Fellow, Zoology

Friday Fellow: Greater Blue-Ringed Octopus

by Piter Kehoma Boll

Tropical waters are always thriving with diversity, therefore it is hard to keep away from them. Today’s Friday Fellow is one more creature from the tropical oceanic waters, more precisely from the Indo-Pacific waters. Being found from Sri Lanka to the Phillipines, Japan and Australia, our fellow is called Hapalochlaena lunulata and popularly known as the greater blue-ringed octopus.

This adorable octopus is very small, measuring only about 10 cm, arms included. It is, however, easy to caught attention because its whitish to dark-yellow body is covered by about 60 rings that show a beautiful electric-blue color with a black outline. As with most octopuses, the color may change according to the animal’s needs in order to make him more or less visible.

A specimen of the greater blue-ringed octopus in Indonesia. Photo by Jens Petersen.*

This adorable color pattern, which may look attractive to us, humans, is nevertheless a warning sign. The grater blue-ringed octopus is a venomous creature and may even kill a human being if threatened. As other octopuses, it is a predator and feeds mainly on crustaceans and bivalves and immobilizes them with a toxin before consumption. This is a mild toxin, though. The real danger is on its defensive behavior.

When threatened, the greater blue-ringed octopus usually begins a warning display by flashing its rings in strong colors. If this is not enough to make the threatening creature retreat, it will atack and bite its harasser. The bite is usually painless but deadly. The venom injected is nothing more nothing less than the infamous tetrodoxin, the same thing that makes a pufferfish a dangerous meal. As you may know, tetrodoxin is a potent neurotoxin that kills within a few minutes to a few hours by blocking the action potential in cells, leading to paralysis and death by asphyxia. In the greater blue-ringed octopus, tetrodotoxin is produced by bacteria that live inside their salivary glands.

800px-blue-ringed_octopus_281428061429929

A greater blue-ringed octopus swimming. Photo by Elias Levy.**

A study analyzing the sexual behavior of the greater blue-ringed octopus showed that mating occurs during encounters of both male-female and male-male pairs. The mating ritual of octopuses consists of the male introducing the hectocotylus, a modified arm specialized in delivering sperm, into the female mantle. In male-male pairings, one of the males always put its hectocotylus into the other male’s mantle and there was no attempt from the receptive male to avoid the act. The only difference between males mating with females or with other males was that they only delivered sperm to females and never to males. What can we conclude? Have octopuses found an efficient way to be bisexual creatures by having fun with other males while still able to keep their sperm to give it to females?

The diversity of life always fascinates us!

– – –

Like us on Facebook!

Follow us on Twitter!

– – –

References:

Cheng, M. W.; Caldwell, R. L. (2000) Sex identification and mating in the blue-ringed octopus, Hapalochlaena lunulataAnimal Behavior 60: 27-33. DOI: 10.1006/anbe.2000.1447

Mäthger, L. M.; Bell, G. R. R.; Kuzirian, A. M.; Allen, J. J.; Hanlon, R. T. (2012) How does the blue-ringed octopus (Hapalochlaena lunulata) flash its blue rings? Journal of Experimental Biology 215: 3752-3757. DOI: 10.1242/jeb.076869

– – –

*Creative Commons License
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

**Creative Commons License
This work is licensed under a Creative Commons Attribution 2.0 Generic License.

Leave a comment

Filed under Friday Fellow, mollusks, Zoology

Friday Fellow: Dead Man’s Rope

by Piter Kehoma Boll

Widespread in northern temperate waters of the Atlantic and Pacific oceans, today’s Friday Fellow is a brown alga whose scientific name, Chorda filum, meaning “rope thread” is a good way to describe its appearance. Its fronds are long and unbranched, measuring about 5 mm in diameter and reaching up to 8 m in length, so that it actually looks like a long rope, which led to common names such as dead man’s rope, sea lace, cat’s gut, bootlace weed, mermaid’s tresses and mermaid’s fishing line.

20118_orig

A group of dead man’s ropes growing together. Credits to Biopix: JC Schou.

This alga is usually found in sheltered areas, such as lagoons, inlets, small bays, fjords and even river estuaries, being very tolerant to waters with low salinity, but avoiding open, exposed beaches. It grows attached to the substrate by a small disc, being usually attached to a very unstable substrate, such as loose pebbles or over other algae, being rarely found on stable rocks. As a result, during events in which the water becomes agitated, such as during storms, it can be easily transported to other localities.

Several species live on the fronds of the dead man’s rope, including many algae and sea snails. Other invertebrates, such as amphipods, does not seem to like it very much.

Studies have shown that the dead man’s rope is rich in antioxidants, compounds that help in reducing the aging process and decrease the risk of diseases such as cancer. Although edible, the dead mean’s rope is not widely used as a food source. Perhaps we could change that, providing it is done in a sustainable way.

– – –

Like us on Faceebok!

Follow us on Twitter!

– – –

References:

Pereira, L. (2016) Edible Seaweeds of the World, CRC Press, London, 463 pp.

South, G. R.; Burrows, E. M. (1967) Studies on marine algae of the British Isles. 5. Chorda filum (L.) StackhBritish Phycological Bulletin3(2): 379-402.

Yan, X.; Nagata, T.; Fan, X. (1998) Antioxidative activities in some common seaweedsPlant Foods for Human Nutrition 52: 253-262.

Leave a comment

Filed under Algae, Friday Fellow

Friday Fellow: Brown Mussel

by Piter Kehoma Boll

Until now, the mollusks featured here included a chiton, a cephalopod and two gastropods. So it is time to bring a bivalve. And what would be better than showing you a common mollusk from the South Atlantic Ocean?

Living on rocky shores around South America and Africa, our fellow is called Perna perna, or populary brown mussel. In places where it lives, it can be found in great concentrations, sometimes covering large areas of rocks. It usually measures about 90 mm in length, but some larger specimens may reach up to 120 mm. The increased surface area on the rocks they occupy attract other rock-living marine species, such as barnacles, limpets, snails and algae.

Perna_perna

Some specimens of Perna perna growing on an oyster in South Africa. Photo by Bernadette Hubbart.*

The brown mussel is a filter feeder, as most bivalves, feeding on suspended organic matter, as well as on small microrganisms, such as phytoplankton and zooplankton. As a prey, it is eaten by a variety of animals, such as sea birds, crustaceans and mollusks. Humans also consume it in both South America and Africa. Its ingestion, however, must be cautious, as it may contain toxins from dinoflagellates that it ingested, as well as heavy metals from water pollutants.

Spread through the world by humans after attaching itself on ships, the brown mussel has become invasive in other parts, especially in the Gulf of Mexico, and it continues to increase its occupied area. This can have deleterious effects both ecologically and economically, as it may displace native species and also cause damage to human equipments. It is, therefore, one more species that became a problem due to us, humans. And the damage will not be easy to be repared.

– – –

Likes us on Facebook!

– – –

References:

Ferreira, A. G.; Machado, A. L. S.; Zalmon, I. R. (2004) Temporal and spatial variation on heavy metal concentrations in the bivalve Perna perna (LINNAEUS, 1758) on the northern coast of Rio de Janeiro State, Brazil. Brazilian Archives of Biology and Technology 47(2): 319–327. http://dx.doi.org/10.1590/S1516-89132004000200020

Holland, B. S. (2001) Invasion without a bottleneck: microsatellite variation in natural and invasive populations of the brown mussel Perna perna (L). Marine Biotechnology 3, 407–415. https://dx.doi.org/10.1007/s1012601-0060-Z

Wikipedia. Perna perna. Available at: < https://en.wikipedia.org/wiki/Perna_perna >. Access on October 21, 2017.

– – –

*Creative Commons License
This work is licensed under a Creative Commons Attribution-NoDerivs 2.0 Generic License.

Leave a comment

Filed under Friday Fellow, mollusks, Zoology

Friday Fellow: Common Latticed Sponge

by Piter Kehoma Boll

Let’s go back to the sea and to our distant animal relatives, the sponges. Today I’m bringing a calcareous sponge with a nice appearance, Clathrina clathrus, who I decided to call “the common latticed sponge”.

Found in the Mediterranean Sea and the European coast of the Atlantic Ocean, the common latticed sponge has a yellow color and about 10 cm in diameter. It is formed by a tangle of tubes that somewhat resemble a twisted lattice or something like that.

450px-clathrina_clathrus_scarpone_055

A specimen of Clathrina clathrus with its latticed appearance. Photo by Wikimedia user Esculapio.*

The shape and size of the specimens is quite variable, changing in a matter of hours by expansion, contraction and folding of structures and cells. In the same way, specimens often fragment into smaller ones or merge into larger ones, so that individuality is a dynamic process.

Recently, the common latticed sponge has revealed to contain some compounds, known as clathridimines, that show antimicrobial activities against Gram-positive and Gram-negative bacteria, as well as against the yeast Candida albicans. These compounds may be produced by the diverse community of bacteria that live in close association with this sponge, a community that is yet very little known.

– – –

Like us on Facebook!

– – –

References:

Gaino, E.; Pansini, M.; Pronzato, R.; Cicogna, F. (1991) Morphological and structural variations in Clathrina clathrus (Porifera, Calcispongiae). In.: Reitner, J.; Keupp, H. (Eds.) Fossil and Recent Sponges. Springer-Verlag, Berlin. pp. 360-371.

Quévrain, E.; Roué, M.; Domart-Coulon, I.; Bourguet-Kondracki, M.-L. (2014) Assessing the potential bacterial origin of the chemical diversity in calcareous sponges. Journal of Marine Science and Technology 22(1): 36-49.

Roué, M.; Domart-Coulon, I.; Ereskovsky, A.; Djediat, C.; Perez, T.; Bourguet-Kondracki, M.-L. (2010) Cellular localization of clathridimine, an antimicrobial 2-aminoimidazole alkaloid produced by the Mediterranean calcerous sponge Clathrina clathrusThe Journal of Natural Products 73(7): 1277–1282.

– – –

*Creative Commons License
This work is licensed under a Creative Commons Attribution 3.0 Unported License.

Leave a comment

Filed under Friday Fellow, sponges

Friday Fellow: Hummingbird Bobtail Squid

by Piter Kehoma Boll

If you are digging through the sand at the bottom of the clear tropical waters around Indonesia and the Philippines, you may end up finding a colorful little creature, the hummingbird bobtail squid, Euprymna berryi, also known as Berry’s bobtail squid.

Euprymna_berryi

A beautiful specimen photographed in East Timor. Photo by Nick Hobgood.*

Measuring about 3 cm if male or 5 cm if female, the humminbird bobtail squid is actually more closely related to cuttlefish than to true squids. Its body has a translucent skin marked by many black chromatophores, and to the human eye the animal seems to have a color pattern formed by a blend of black, electric blue and green or purple dots.

During the day, the hummingbid bobtail squid remains most of the time buried in the sand, coming out at night to capture small crustaceans, which it hunts using a bioluminescent organ in its gill cavity.

In some areas around its distribution, the hummingbid bobtail squid is captured and sold in small fisheries, but as the data on the distribution and population dynamics of this species are very poorly known, there is no way to say whether it is vulnerable or endangered in any way. As a result, it is listed as Data Deficient in the IUCN Red List.

– – –

ResearchBlogging.orgReferences:

Barratt, I., & Allcock, L. (2012). Euprymna berryi The IUCN Red List of Threatened Species DOI: 10.2305/IUCN.UK.2012-1.RLTS.T162599A925343.en

Wikipedia. Euprymna berryi. Available at <https://en.wikipedia.org/wiki/Euprymna_berryi&gt;. Access on March 8, 2017.

– – –

*Creative Commons License
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

Leave a comment

Filed under Friday Fellow, mollusks, Zoology