Category Archives: Facts

Short, Single Subject posts

Fade with the darkness

Butterflyfish fact
Butterflyfish Fact

At night, butterflyfish settle into dark crevices, and their brilliant colors and markings fade to blend with the reef background.

The butterflyfish are a group of conspicuous tropical marine fish of the family Chaetodontidae

Etymology
Chaetodontidae – The family name from Ancient Greek words χαιτέ, chaite ‘hair’ + οδοντος, odontos ‘tooth.’ This is an allusion to the rows of brush-like teeth found in their small, protrusible mouths.

Pretty in Pink

Beach Fact
Beach Fact

Pink Sand is thanks to a species of microscopic creatures call foraminfera

They live on the underside of reefs, and when their tiny red shells (test) wash ashore, they mix with bits of whit coral for a pretty pastel in pink.

Foraminfera are members of a phylum of amoeboid protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly an external shell (called a “test”) of diverse forms and materials. Foraminifera typically produce a test, or shell, which can have either one or multiple chambers, some becoming quite elaborate in structure. These shells are commonly made of calcium carbonate (CaCO3) or agglutinated sediment particles. Over 50,000 species are recognized, both living (10,000) and fossil (40,000). They are usually less than 1 mm in size.

Dying planktonic Foraminifera continuously rain down on the sea floor in vast numbers, their mineralized tests preserved as fossils in the accumulating sediment. Deep Sea Drilling, have been bringing up sediment cores bearing Foraminifera fossils. The effectively unlimited supply of these fossil tests and the relatively high-precision age-control models available for cores has produced an exceptionally high-quality planktonic Foraminifera fossil record dating back to the mid-Jurassic, and presents an unparalleled record for scientists testing and documenting the evolutionary process. The exceptional quality of the fossil record has allowed an impressively detailed picture of species inter-relationships to be developed on the basis of fossils.

Etymology
foraminfera – Latin for ‘hole bearers’

Sperm whale communication differences lean towards culture

 A study published in Behavior Genetics suggests that sperm whale groups are made up of individuals that use the same dialect, rather than those that come from a similar area of the Pacific.

In the Pacific, sperm whales belong to one of five clans. Each use a different dialect made up of a different handful of similar Morse code-like patterned clicks called codas. The clicks may be employed to communicate that they belong to a particular pod and to maintain social bonds. The whales create the sounds in the “big tub of oil at the front of their huge heads”, explained Luke Rendell from the University of St Andrews.  Along with air sacs in the whales’ heads, the structure produces multiple pulses, just fractions of a second apart.

SpermWhaleCodas2

Rendell contemplated whether the difference between whale clans was down to genetics. “What are the genetics of these populations? Are these dialects culturally transmitted or genetic?” Rendell and colleagues from the US and Canada analyzed DNA from the sloughed skin of 194 sperm whales belonging to 30 different social groups from three of the vocal clans across the Pacific Ocean.

Once the dialects were biologically determined, it was surmised that those sharing the same dialect would have similar genes. Instead, they found that whales with different repertoires of codas are often genetically similar, suggesting that the genetic differences don’t explain clan differences and that dialects must be passed down through the generations. Not only do the clans possess different dialects, they also had different hunting patterns, parenting habits, and reproductive rates.

All the evidence for culture relies on methods of exclusion. It’s very difficult to actually prove cultural transmission,” stated Rendell. “But our finding isn’t consistent with anything other than cultural dialects.”Findings from this research could help influence conservation efforts; instead of solely focusing on the animals’ habitat, protection should also consider which dialect they use.

We hope our finding will get people thinking about conservation, and the idea that behavior in marine mammals is culturally-determined,”  Rendell said.

Whale blowhole Fact

Humpback Whale and Sperm Whale
Blowing hot air.

Whale Fact:

Baleen Whales – those whales who do not have teeth, but rather have baleen plates to filter food out of the water – have two blowholes, while toothed whales have just one blowhole.

Odyssey Expeditions Whale Encounters

During the summer Adventure Voyages we occasionally see Atlantic Bottle Nose Dolphins (Tursiops truncatus)  in the British Virgin Islands.  We have had several dives where the dolphins have stayed and played with dives for 15 minutes.  Larger migratory whales visit the BVIs during the winter.

The S.E.A voyages in the Grenadines we have seen a pod of Killer Whales (Orcinus orca) that swam for over 30 minutes with the yacht while sailing .  We commonly see Short Finned Pilot Whales (Globicephala macrorhynchus) at a distance and we see Atlantic Bottle Nose (Tursiops truncatus) and Spinner Dolphins (Stenella longirostris) that are famous for its acrobatic displays in which it spins along its longitudinal axis as it leaps through the air.

Sea Turtle Nesting Fact:

Adult female sea turtles are literally magnetically drawn to the comforting beaches where they were hatched.   Sea turtles imprint on the unique magnetic field of their natal beach as hatchlings and then use this information to return as adults.

Scientists suspect that tiny magnetic particles in sea turtle brains enable them to detect unique magnetic signatures given off by beaches, such that they can return to them after ultra long journeys.

What’s good for mother turtle is good for her adult offspring too, since the latter don’t bother trying to hunt down better beaches. Mom’s choice is the only one.

Sea Turtle Nesting
A loggerhead sea turtle nesting