Five views of a shell of the Giant Tun Snail - Tonna galea, a species of marine gastropod mollusc in the family Tonnidae. The shell is very large, with an average height of 6 in (150 mm), but thin and inflated (though durable); as such, the shell weighs considerably less than comparable gastropod shells.

top - from left to right: Dorsal, lateral (right side), ventral, back, and front view.

  Photographs: H. Zell; edit: Heinrich Pniok and Vouliagmeni

(via: Wikipedia)

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Tiger Egg Cowrie - Cuspivolva tigris | ©Ülar Tikk   (Lembeh, Indonesia)
This beauty is a live Cuspivolva tigris (Gastropoda - Ovulidae), showing the brightly colored mantle covering the shell and the siphon (left side).
The siphon is an anterior extension of the mantle, through which water is drawn into the mantle cavity and over the gill for respiration. 
The mantle is orange-yellow and has black patches with white border, due to this and the ovoid shape of the shell, this species is commonly known as Tigger egg cowrie.

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Tiger Egg Cowrie - Cuspivolva tigris | ©Ülar Tikk   (Lembeh, Indonesia)

This beauty is a live Cuspivolva tigris (Gastropoda - Ovulidae), showing the brightly colored mantle covering the shell and the siphon (left side).

The siphon is an anterior extension of the mantle, through which water is drawn into the mantle cavity and over the gill for respiration. 

The mantle is orange-yellow and has black patches with white border, due to this and the ovoid shape of the shell, this species is commonly known as Tigger egg cowrie.

Opalescent Sea Slug, Hermissenda crassicornis
- Lampton Cliffs County Park, Cambria, CA, USA
One of the most abundant nudibranchs in Califonia, it eats hydroids, but the diet also includes small sea anemones, bryozoans, colonial ascidians (Aplidium solidum, botryllids), annelids, small crustacea, tiny clams, dead animals of any sort. It will also eat other Hermissenda. In the Puget Sound, Hermissenda is the main predator of the sea pen Ptilosarcus gurneyi.
Mating animals are most often found in southern California in winter, but are found year around in the Puget Sound (Washington). The egg string resembles linked pink sausages. They are commonly attached to algae and to blades of eelgrass. Each egg case usually contains one egg, but can contain up to four.
Many studies have been carried out on Hermissenda, but the main area of focus is the eye. It has five cells, each about 75 um in diameter, which are large enough to receive a recording electrode. Within the cells it is suspected of containing symbiotic fungi. Hermissenda is an aggressive creature. When two individuals encounter fights will break out, which involves lunging and biting. Encounters most likely to induce a fight are those of mutual head on contact. The individual whose head is closest to the others tail or side will usually get the first bite in, this also means that they usually come out the winner.
The copepod Hemicyclops thysanotus is often found adhering to the dorsal surface of Hermissenda. The nudibranch Phidiana hiltoni may attack this nudibranch.
text by Rosario Beach Marine Laboratory
photo by Ken-ichi Ueda 
(via: Encyclopedia of Life)

Opalescent Sea Slug, Hermissenda crassicornis

- Lampton Cliffs County Park, Cambria, CA, USA

One of the most abundant nudibranchs in Califonia, it eats hydroids, but the diet also includes small sea anemones, bryozoans, colonial ascidians (Aplidium solidum, botryllids), annelids, small crustacea, tiny clams, dead animals of any sort. It will also eat other Hermissenda. In the Puget Sound, Hermissenda is the main predator of the sea pen Ptilosarcus gurneyi.

Mating animals are most often found in southern California in winter, but are found year around in the Puget Sound (Washington). The egg string resembles linked pink sausages. They are commonly attached to algae and to blades of eelgrass. Each egg case usually contains one egg, but can contain up to four.

Many studies have been carried out on Hermissenda, but the main area of focus is the eye. It has five cells, each about 75 um in diameter, which are large enough to receive a recording electrode. Within the cells it is suspected of containing symbiotic fungi. Hermissenda is an aggressive creature. When two individuals encounter fights will break out, which involves lunging and biting. Encounters most likely to induce a fight are those of mutual head on contact. The individual whose head is closest to the others tail or side will usually get the first bite in, this also means that they usually come out the winner.

The copepod Hemicyclops thysanotus is often found adhering to the dorsal surface of Hermissenda. The nudibranch Phidiana hiltoni may attack this nudibranch.

text by Rosario Beach Marine Laboratory

photo by Ken-ichi Ueda

(via: Encyclopedia of Life)

Time May Be Running Out for These Gorgeous Jewel-Like Snails

by Nadia Drake

Tiny tropical snails with beautiful, jewel-like shells are going extinct almost as fast as scientists can discover them. The minute mollusks, which average just 1 to 3 millimeters long, are members of the genus Plectostoma. Their shells are elaborate and irregularly coiled, unlike the snail shells we’re used to seeing.

Plectostoma make their homes on the lichens and moss that cover limestone hills of peninsular Malaysia and other parts of southeast Asia; they don’t get around that much, so it’s not uncommon for different hills to host separate species that are found only on that one hill, say the scientists who published a report documenting 31 species of spectacular snails, including 10 previously undescribed, today in Zookeys. The team used old collections, new observations, and CT scans of shell shapes to determine which snails belonged to which species…

(read more: Wired Science)

photographs by Thor-Seng Liew

Meet the White-line Dirona 
Not just another pretty… face (?) this nudibranch boasts jaws that can crack open snail shells. This generalist predator also enjoys sea anemone, hydroid and sea squirts, though. For you sea slug fanciers, this animal does look a lot like an Eolid nudibranch, because of the beautiful cerata all over its back. You can tell an Eolid from an Arminacean like this one by the position of the anus. If you simply must know more about that… 
read more: Encyclopedia of Life But however much you might feel inclined to check, please think twice before handling this animal. The cerata fall off quite easily, according to our friends at the Rosario Beach Marine Lab. Photo: Gerald and Buff Corsi via CalPhotos

Meet the White-line Dirona

Not just another pretty… face (?) this nudibranch boasts jaws that can crack open snail shells. This generalist predator also enjoys sea anemone, hydroid and sea squirts, though.

For you sea slug fanciers, this animal does look a lot like an Eolid nudibranch, because of the beautiful cerata all over its back. You can tell an Eolid from an Arminacean like this one by the position of the anus. If you simply must know more about that…

read more: Encyclopedia of Life

But however much you might feel inclined to check, please think twice before handling this animal. The cerata fall off quite easily, according to our friends at the Rosario Beach Marine Lab.

Photo: Gerald and Buff Corsi via CalPhotos

Cone snail drug 100x more potent than morphine
by  AG Staff 
A new drug from cone snail venom could offer hope to chronic pain sufferers
AN EXPERIMENTAL DRUG made from cone snail venom has shown early signs of promise in numbing pain, raising hopes in the hunt for new, non-addictive medications, an Australian researcher says.
The drug, which has not been tested yet on humans, is judged to be about 100 times more potent than morphine or gabapentin, which are currently considered the gold standard for chronic nerve pain.
The active ingredient, conotoxin, comes from carnivorous cone snails, which are common in the western Pacific and Indian Ocean…
 (via: Australian Geographic) 
image: Australian cone snail (Conus textile), with proboscis extended and poised for attack. Image Credit: AAP Image/Melbourne University/David Paul

Cone snail drug 100x more potent than morphine

by  AG Staff

A new drug from cone snail venom could offer hope to chronic pain sufferers

AN EXPERIMENTAL DRUG made from cone snail venom has shown early signs of promise in numbing pain, raising hopes in the hunt for new, non-addictive medications, an Australian researcher says.

The drug, which has not been tested yet on humans, is judged to be about 100 times more potent than morphine or gabapentin, which are currently considered the gold standard for chronic nerve pain.

The active ingredient, conotoxin, comes from carnivorous cone snails, which are common in the western Pacific and Indian Ocean…

(via: Australian Geographic)

image: Australian cone snail (Conus textile), with proboscis extended and poised for attack. Image Credit: AAP Image/Melbourne University/David Paul

astronomy-to-zoology

astronomy-to-zoology:

Emerald Green Snail (Papustyla pulcherrima)

Also known as the Green Tree Snail or Manus Green Tree Snail, the emerald green snail is a species of terrestrial camaenid gastropod that is endemic to Manus Island in Papua New Guinea. Emerald green snails typically inhabit rain forests and are usually found in trees.

Although Papustyla pulcherrima is listed as Data Deficient by the IUCN it faces severe threats due to overharvesting for commercial purposes and habitat loss.

Classification

Animalia-Mollusca-Gastropoda-Heterobranchia-Euthyneura-Panpulmonata-Eupulmonata-Stylommatophora-Sigmurethra-Helicoidea-Camaenidae-Papustyla-P. pulcherrima

Images: Dennis Hill and Tim Ross

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Kleptoplasty: an unique trophic strategy
Kleptoplasty or kleptoplastidy is a symbiotic phenomenon whereby plastids, (notably chloroplasts), from algae are sequestered by host organisms. The alga is eaten normally and partially digested, leaving the plastid intact. The plastids are maintained within the host, temporarily retaining functional photosynthesis for use by the predator [1].
This phenomenon occurs in some unicellular organisms such as foraminifera, dinoflagellates and ciliates, but also in a few multicellular organisms.
Among metazoans, retention of functional diet-derived chloroplasts (kleptoplasty) is known only from the sea slug taxon Sacoglossa (Gastropoda - Opisthobranchia). Intracellular maintenance of plastids in the slug’s digestive epithelium has long attracted interest given its implications for understanding the evolution of endosymbiosis.
According to a paper published by Händeler et al. (2011), photosynthetic ability varies widely among sacoglossans; there are three levels of photosynthetic activity: (a) no functional retention; (b) short-term retention lasting about one week; and (c) long-term retention for over a month. 
Elysia crispata is one of the species that has a long-term chloroplast retention ability, where other species within the same genus tend to have more short-term retention.
This species can be either heterotrophic or autotrophic throughout their lifespan. As juveniles, food is consumed and digested quickly, with little chloroplast retention. Upon reaching maturity, kleptoplasty becomes an important energy source [3]. Chloroplasts within their parapodia (fleshy dorsal protrusions) continue to produce energy products through carbon fixation throughout their life.
Image: Elysia crispata - ©Zsuzsanna Pusztai

libutron:

Kleptoplasty: an unique trophic strategy

Kleptoplasty or kleptoplastidy is a symbiotic phenomenon whereby plastids, (notably chloroplasts), from algae are sequestered by host organisms. The alga is eaten normally and partially digested, leaving the plastid intact. The plastids are maintained within the host, temporarily retaining functional photosynthesis for use by the predator [1].

This phenomenon occurs in some unicellular organisms such as foraminifera, dinoflagellates and ciliates, but also in a few multicellular organisms.

Among metazoans, retention of functional diet-derived chloroplasts (kleptoplasty) is known only from the sea slug taxon Sacoglossa (Gastropoda - Opisthobranchia). Intracellular maintenance of plastids in the slug’s digestive epithelium has long attracted interest given its implications for understanding the evolution of endosymbiosis.

According to a paper published by Händeler et al. (2011), photosynthetic ability varies widely among sacoglossans; there are three levels of photosynthetic activity: (a) no functional retention; (b) short-term retention lasting about one week; and (c) long-term retention for over a month. 

Elysia crispata is one of the species that has a long-term chloroplast retention ability, where other species within the same genus tend to have more short-term retention.

This species can be either heterotrophic or autotrophic throughout their lifespan. As juveniles, food is consumed and digested quickly, with little chloroplast retention. Upon reaching maturity, kleptoplasty becomes an important energy source [3]. Chloroplasts within their parapodia (fleshy dorsal protrusions) continue to produce energy products through carbon fixation throughout their life.

Image: Elysia crispata©Zsuzsanna Pusztai

In New Study, Scientists Propose That a Handful of Species Types Are Key Are to Ecosystem Health
by Ariel Mark
While conducting field research in the humid salt marshes of Sapelo Island, scientists Marc Hensel and Brian Silliman made an astonishing discovery: species type, not just quantity, is vital for maintaining healthy ecosystems.
For decades, scientists believed that preserving the largest number of species was critical for ecosystem function, regardless of their genetic makeup. However, Hensel, a PhD student at the University of Massachusetts at Boston, and Silliman, Rachel Carson Associate Professor at Duke University, counter the old dogma in an article recently published in Proceedings of the National Academy of Sciences.
By examining the relationships among three dominant consumer species (i.e., grazers and predators), Hensel and Silliamn found that it isn’t just the number of total species, but the number of specific species that is crucial to upholding ecosystem performance.
Working in the cordgrass (Spartina alterniflora) dominated salt marshes of Sapelo Island in the Southeastern U.S. state of Georgia, the researchers measured the effect of species loss on ecosystem performance. Salt marshes are seemingly simple ecosystems composed of a few extremely abundant and influential species…
(read more: MongaBay)
photograph of marsh periwinkle snail (Litoraria irrorata)by Mary Hollinger

In New Study, Scientists Propose That a Handful of Species Types Are Key Are to Ecosystem Health

by Ariel Mark

While conducting field research in the humid salt marshes of Sapelo Island, scientists Marc Hensel and Brian Silliman made an astonishing discovery: species type, not just quantity, is vital for maintaining healthy ecosystems.

For decades, scientists believed that preserving the largest number of species was critical for ecosystem function, regardless of their genetic makeup. However, Hensel, a PhD student at the University of Massachusetts at Boston, and Silliman, Rachel Carson Associate Professor at Duke University, counter the old dogma in an article recently published in Proceedings of the National Academy of Sciences.

By examining the relationships among three dominant consumer species (i.e., grazers and predators), Hensel and Silliamn found that it isn’t just the number of total species, but the number of specific species that is crucial to upholding ecosystem performance.

Working in the cordgrass (Spartina alterniflora) dominated salt marshes of Sapelo Island in the Southeastern U.S. state of Georgia, the researchers measured the effect of species loss on ecosystem performance. Salt marshes are seemingly simple ecosystems composed of a few extremely abundant and influential species…

(read more: MongaBay)

photograph of marsh periwinkle snail (Litoraria irrorata)by Mary Hollinger