Tag Archives: sea creatures

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.

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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.

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Friday Fellow: Branching Vase Sponge

by Piter Kehoma Boll

A fascinating group of animals that has not yet joined the Friday Fellows are the sponges. Different from all other animals, sponges have a unique body structure that behaves more like a plant or fungus. They grow in irregular or radial ways and are usually branched. More than that, they have thousands of small mouths along their bodies, called pores, that suck water from the environment in order to filter food from it.

But let’s talk about our species. Living in the Caribbean Sea, its name is Callyspongia vaginalis, commonly known as branching vase sponge. Its usual shape is that of a tube or set of tubes, sometimes branched, that may reach several centimeters in length and usually abour 3 cm in diameter. The color may vary from pink or lavender to duller colors, such as brown or gray.

callyspongia_vaginalis

A lavender pipe of Callyspongia vaginalis. Photo by Mark Rosenstein*.

As most sponges, the branching vase sponge feeds on small particles and microorganisms that it filters from water. As the concentration of particles in the water increases with depth, organisms growing deeper usually grow faster due to the higher food availability.

The main predators of the branching vase sponge are fishes. They actually act more like herbivores eating plants, as they don’t eat the whole sponge and usually do not kill it, but bite its surface, taking off pieces.

callyspongia_vaginalis2

A large and branched individual of the branching vase sponge. Photo by Paul Asman and Jil Lenoble.**

Bristlestars, especially of the genus Ophiothrix, such as Ophiothrix lineata, are frequently found living inside the main cavity of the sponge. There, these animals find shelter from predators and, at night, when the environment is safer, they extend their arms outside and clean the sponge from large organic particles, feeding on them. It’s a mutually benefitial association.

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ResearchBlogging.orgReferences:

EOL – Encyclopedia of Life. Callyspongia vaginalis. Available at <http://eol.org/pages/1163688/overview&gt;. Access on January 12, 2017.

Hendler, G. (1984). The Association of Ophiothrix lineata and Callyspongia vaginalis: A Brittlestar-Sponge Cleaning Symbiosis? Marine Ecology, 5 (1), 9-27 DOI: 10.1111/j.1439-0485.1984.tb00304.x

Hoppe, W. (1988). Growth, regeneration and predation in three species of large coral reef sponges Marine Ecology Progress Series, 50, 117-125 DOI: 10.3354/meps050117

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Filed under Friday Fellow, sponges

Friday Fellow: Royal sea star

ResearchBlogging.orgby Piter Kehoma Boll

In order to celebrate the 5oth Friday Fellow, which was posted today, I decided to bring you an extra Friday Fellow! Afterall, there are plenty of interesting lifeforms to be shown.

As I have never presented you any echinoderm, I thought it would be interesting to start the second group of 50 FFs with one of them. So I’ve chosen the royal sea star (Astropecten articulatus).

Beautiful colors, don't you think? Photo by Mark Walz.*

Beautiful colors, don’t you think? Photo by Mark Walz.*

Found in waters from 0 to 200 m deep the West Atlantic coast from New Jersey to Uruguay, the royal sea star may reach around 20 cm in diameter and is easily identified by its color. Dorsally it has a series of dark blue to purple granulose papilae and is lined by orange marginal plates with supermarginal white spines that give it a comb-like appearence, hence the name “Astropecten“, meaning “star-comb”.

As most starfishes, the royal starfish is a predator. It feeds mainly on small and medium-sized mussels and ingests the prey intact, digesting it inside its mouth. As it is unable to digest food extraorally (outside its mouth) it cannot feed on anything that cannot be ingested whole.

Most of its activity occurs at dawn and dusk, which may be inversely related to the activity of predatory fish, as those are usually more active during the day.

Being a considerably common starfish, you may easily find one while walking on the beach, provided that the beach is at the right place.

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References:

Beddingfield, S., & McClintock, J. (1993). Feeding behavior of the sea star Astropecten articulatus (Echinodermata: Asteroidea): an evaluation of energy-efficient foraging in a soft-bottom predator Marine Biology, 115 (4), 669-676 DOI: 10.1007/BF00349375

Wikipedia. Astropecten articulatus. Availabe at: <https://en.wikipedia.org/wiki/Astropecten_articulatus >. Access on July 28, 2016.

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Filed under Conservation, Echinoderms, Friday Fellow, Zoology