Archive for the Natural History Category

‘Man O War’

Monday, May 2nd, 2011

‘Man O War’
Physalia physalis
Film + Aquarium: Morphologic
Original Soundtrack: Geologist

In this special installment of our Natural History film series, Geologist soundtracks a macroscopic view of a Portuguese man-o-war’s beautiful, yet highly venomous tentacles.

The man-o-war is often mistaken as a jellyfish, but this is not the case. It does not swim, but is instead propelled by the winds, tides and currents across the ocean’s surface. In fact, a man-o-war is not even a single organism, but an entire colony of organisms called siphonophores, that live together as a singular unit. They are found floating across all of the world’s tropical and subtropical oceans. Even more impressive is that the man-o-war colony is comprised of four different types of polyps, called zooids, that each serve a different purpose to the overall functioning of the colony.

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‘The Squat Urchin Shrimp’

Monday, June 28th, 2010

‘The Squat Urchin Shrimp’
Gnathophylloides mineri on Tripneustes ventricosus
Music, Video, and Aquarium
2010 Morphologic Studios

The Squat Urchin Shrimp (Gnathophylloides mineri) is an amazingly successful creature that can be found living amongst the spines of sea urchins throughout most of the world’s shallow tropical waters. In the Caribbean they hitchhike exclusively upon the black and white West Indian Sea Egg (Tripneustes ventricosus), traveling along where ever its host may go. The squat urchin shrimp is very small, reaching no more than 6mm in length, and orients itself parallel with the spines making it all but invisible and protected from a would-be-predator. Often colonies of up to half a dozen squat urchin shrimp of varying sizes will all share the same urchin. Beyond its circumtropical distribution and perfect camouflage, the squat urchin shrimp further demonstrates its successfulness by feeding upon the epidermal tissue of the very spines that grant it protection. This is a relatively benign form of parasitism that doesn’t seem to bother the urchin. These shrimp will also feed opportunistically upon detritus that the urchin picks up as it moves along the sea floor. The squat urchin shrimp is a creature that has found a near perfect niche in a truly self-sustaining, self-contained world of spines.

‘The Heart Urchin Pea Crab’

Monday, June 21st, 2010

‘The Heart Urchin Pea Crab’
Dissodactylus primitivus on Meoma ventricosa
Music, Video, and Aquarium
2010 Morphologic Studios

Barely 7mm in size, the aptly named heart urchin pea crab (Dissodactylus primitivus) lives its entire life as a passenger upon the slow-moving red heart urchin (Meoma ventricosa). It is an example of the unusual life that can be found by looking in unexpected places on Floridian coral reefs. The red heart urchin is an unusual member of the echinoderm clan (e.g. urchins, sea stars, sand dollars, sea cucumbers) that spends most of its time burrowing in the sand. It sifts through the grains of sand searching for organic detritus that constitutes its diet. Likewise, the heart urchin pea crab lives a well-protected life (usually below the sand) amongst the spines of this fist-sized urchin. While most crabs move swiftly, this pea crab moves slowly in order to navigate through the corridors of spines, even spending time inside the urchin’s mouth. It is likely that the crab feeds upon some of the food that would otherwise be consumed by the urchin. This commensal relationship appears mildly parasitic, as the urchin doesn’t seem to gain any sort of direct benefit from the crab living amongst its spines. Frequently, several heart urchin pea crabs will live communally without any noticeable negative impact to their host urchin’s health.

If you look closely, you’ll notice the rhythmic working of its gills and circulatory system within the heart urchin pea crab’s translucent, eggshell exoskeleton.

‘Cleaner’ Pt. 3

Tuesday, June 15th, 2010

‘Cleaner’ Pt. 3
Periclimenes rathbunae on Stichodactyla helianthus
Music, Video, and Aquarium
2010 Morphologic Studios

The sun anemone shrimp (Periclimenes rathbunae) is the least common of the three species of Floridian anemone shrimp. While the other two anemone shrimp (P. pedersoni and P. yucatanicus) act as cleaners to passing fish, the sun anemone shrimp doesn’t seem to engage in this behavior. Instead, it spends its time living almost exclusively upon its namesake sun anemone (Stichodactyla helianthus). Aquarium observations suggest that this shrimp may supplement its diet by occasionally nipping off and eating the tentacles of the anemone. This parasitism suggests a more complicated symbiotic relationship than the sort of simple mutualism that these shrimp are often categorized by.

In Floridian waters, the scarcity of this shrimp is likely related to the infrequency of its host sun anemone. However, where they are found, the sun anemone often lives in dense clonal colonies that can literally carpet shallow reefs. The tentacles, while short and stubby, are packed with powerful stinging nematocysts that act like microscopic harpoons to deliver their venom. The end result of all these nematocysts and tentacles, is an anemone that is very ‘sticky’, and capable of producing painful welts to the careless diver.

‘The Porcelain Crab’

Friday, May 28th, 2010

‘The Porcelain Crab’
Petrolisthes galathinus feeding on passing plankton
Music, Video, and Aquarium
2010 Morphologic Studios

The porcelain crab’s common name is derived from its propensity to drop claws like a fragile tea cup breaking. When attacked, the would-be predator is usually left with nothing more than a few amputated (and still-twitching) limbs. In a few days the porcelain crab will undergo an ‘emergency molt’ of its exoskeleton and begin regenerating its lost appendages.

The porcelain crab shown here, Petrolisthes galathinus, is a common resident of Floridian and Caribbean reefs, living under rubble and coral heads. Turning over loose rocks will often yield a fleeting glimpse of scurrying, purple legs. They can move incredibly fast and generally remain cryptic to the passing scuba diver. While many crab species are territorial and agressive towards members of their own species, these porcelain crabs can be colonial with several dozen porcelain crabs living together under the same rock.

Despite the similar appearances, porcelain crabs are not ‘true’ crabs; they are in fact more closely related to the squat lobster clan (Galatheidae) than the archetypal brachyuran crabs we are all familiar with. Porcelain crabs’ flattened bodies are adapted to their life under rocks and in crevices. One of the defining features of porcelain crabs are the comb-like appendages called ‘setae’ that sweep the water currents in order to collect edible particles that happen to float by. Another pair of specialized appendages scrape the the setae and bring the collected food to their mouthparts. This feeding strategy, with its alternating rhythm, appears robotic in its efficiency.

‘Transmission’

Wednesday, May 19th, 2010

‘Transmission’
Pseudoceros crozieri or ‘Tiger Flatworm’
Music, Video, and Aquarium
2010 Morphologic Studios

The tiger flatworm (Pseudoceros crozieri) is a stunning species of flatworm that can be found living on rocks and mangrove roots along the shores of the Caribbean. Colonial orange tunicates (Ecteinascidia turbinata) constitute the tiger flatworm’s only food-source. At 35mm in length, it is considerably larger than the previously featured red flatworms. As simultaneous hermaphrodites, the tiger flatworm often travels as pairs and mate regularly. Their pseudotentacle antennae help aid them in finding mates by detecting chemical cues in the water.

Locomotion in this larger flatworm species is accomplished by rippling muscle contractions along the edges of the animal, and aided by a slippery mucous slime. The video is shown in real time.

‘The Lettuce Slug’

Monday, May 10th, 2010

‘The Lettuce Slug’
Elysia crispata on Halimeda opuntia
Music, Video, and Aquarium
2010 Morphologic Studios

Lettuce sea slugs (Elysia crispata) are a commonly found in protected nearshore Floridian waters where green macroalgae proliferates. They belong to a clan of sea slugs, the sarcoglossans, that are characterized by their ‘sap-sucking’ feeding habits of algae. These slugs slowly patrol mangrove roots and rocks searching for green algae upon which they feed. They store some of the chloroplasts from eaten algae in their tissue, giving it the green coloration. The chloroplasts continue to function, providing the slug with photosynthetic energy. The ruffles along the back of the lettuce sea slug are called parapodia, and help provide more surface area for the chloroplasts to inhabit. They also camouflage the slug amongst the leafy algae that they live amongst. It is very easy to swim past a lettuce nudibranch without ever noticing it.

The scrolled rhinophores (antennae) on the head of the lettuce sea slug help detect the chemical fingerprints of their preferred algal species. If you look carefully, just behind the rhinophores, you’ll notice the small black eye spots that act as rudimentarly eyes to detect changes in light and dark.

The macroalgae featured in the film is Halimeda opuntia, (named after its resemblance to the prickly pear cactus Opuntia sp. ). It is unique amongst green algae in that it produces a semi-rigid, calcareous skeleton. In fact, the dead ‘leaf’ fragments of Halimeda spp. algae are a more significant producer of coral reef sand than the corals themselves. It is not uncommon to find lettuce sea slugs on Halimeda opuntia algae, as it frequently lives amidst the softer green algae that the lettuce sea slugs prefer.