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29

There are very few things in the world that aren't beneficial to some lifeform. Even if you were to, say, spill a mixture of persistent broad-spectrum poisons on an area that killed off 99.9% of all species there, the remaining 0.1% that did survive would benefit from the lack of competition. The "great garbage patch" is hardly so extreme a phenomenon, but ...


26

I'll focus on whales and dolphins (cetaceans) as you mention them by name and they are representative for other marine mammals such as seals or manatees. The evolution of cetaceans was one of the fascinating evolutionary mysteries. Clearly, they were mammals, but which mammals were their closest relatives? Clues to solve this mystery began to appear in the ...


12

In the case of whales, I always thought that it was something to do with the fact that they rely upon buoyancy to support their weight and this seems to support that view: When whales, including small whales or dolphins become stranded on beaches they suffer from the pressure of their own weight on their organs,in the water they are weightless. They ...


11

Cetaceans (i.e., marine mammals) evolved from certain ancient land based mammals, thus the tail is essentially convergent evolution of the tail function.


10

While fish tend to move from side to side (lateral undulation) for which a vertical tail makes sense, the land ancestors of marine mammals had their limbs under them and so their spines were already adapted to up and down movement (dorsoventral undulation). When these animals moved to marine environments, they continued up and down movement in their ...


9

The link you give doesn't mention limbs sticking out of the body wall, but only vestigial hind limb elements. Many whales do retain pelves and femora, as this page at the Bergen Museum shows. Given the variation in limb development across vertebrates, it would not be surprising to find more distal elements (but I would be very surprised if they extended past ...


8

Here there are spectrograms from Bottlenose dolphins (Tursiops truncatus), Killer whales (Orcinus orca) and False killer whales (Pseudorca crassidens). Here there are spectrograms for Humpback whale (Megaptera novaeangliae) and from Sperm whales (Physeter catodon or Physeter marcocephalus) Here there are spectrograms from Blue whale, Fin whale and Minke ...


7

How did they evolve from their original form to their superficially ichthyoid appearance today? This is an example of convergent evolution. Fish appear as they do (streamlined body shape, wide tail, fins, etc.) since these are adaptations to the underwater environment they're living and evolving in. These features are only "ichthyoid" or "fishy" because ...


6

Dolphins can hear above 110 kHz, and produce vocalizations in this range. Clicking has evolved in proposes and sperm whales and is predominantly above 100 kHz (to avoid being heard by killer whales). It's a bit subjective, of course: if you do a frequency decomposition of a click, it will always have some component with very high frequency. That dolphins ...


4

Asterosaponins are the class of compounds - they have a cholesterol like organic core. Apparently, these saponins make pore-forming complexes with Δ5-sterols of cell membranes, and so are deadly to all usual kind of life, including bacteria and fungi. Quote: Starfish and sea cucumber cell membranes are resistant to their own saponines due to the ...


4

This is the one I've heard of - Its a sealed acrylic globe that contains algae and brine shrimp. There are quite a few references in the bibliography here to previous systems. Of course, it needs sunlight, but all the elements are recycled. Its really closed and has reasonable endurance. The basic commercial version of his closed world -- sold under ...


4

The mechanisms of osmoregulation is different for sharks (and other elasmobranch fishes) and teleost fishes. In Elasmobranchs the body osmolarity is maintained equal to the seawater by Na⁺ Cl⁻ and urea. Toxicity because of high concentrations of urea (strong chaotrope) is counteracted by high levels of trimethylamine oxide (TMAO). So, the elasmobranchs do ...


4

I'm not sure that all phytoplankton perform the same type of photosynthesis. Originally, people thought that they all performed C4, on the basis of genome sequencing, which revealed the presence of genes important for C4 photosynthesis. However, experiments on individual species seemed to indicate that the phytoplankton were performing multiple types of ...


4

The various species of nautilus use a combination of active transport of salts and passive diffusion of water for buoyancy (Denton and Gilpin-Brown 1966, Ward 1979, Greenwald et al. 1980). The chambers are filled with seawater. Salts from the seawater in the chambers is removed by a structure called the siphuncular epithelium. This process makes the ...


3

There is a number of reported cases of marine species reaching new locations through "hitchhiking" in recent times. However, it seems harder to find reports of species actually becoming established in a new location through this. The following articles describe examples of species transported with ocean debris: In an early study on the dispersal of ...


3

Viruses hijack the hosts translational machinery, forcing the host to downregulate translation of other proteins in favor of viral proteins. Your cells will eventually lyse, but in the meantime they would not be producing the enzymes required to make whatever product it is you're trying to get, likely resulting in low yields that are contaminated with virus. ...


3

This advice is America-centric; graduate programs in other countries may be different, especially in regards to assigned course work, etc. But this should more-or-less be solid. Also, I'm assuming you're interested in a PhD. I don't know if what you're looking for is a proper field, but that doesn't matter. Ideally, grad school is where you do research on ...


3

A research paper that recently came out suggests that deep-sea life does have a circadian rhythm, but it is regulated much differently than it is by us surface dwellers. We see light, we eat and digest, and the suprachiasmatic nucleus in the brain (our "biological" clock) keeps track of it and eventually establishes a rhythm of the circadian variety. Most ...


2

My first question would be is there any external indication of them such as air holes or anything else that you can assess from the surface? I would think that if there is, you could use transects and a quadrat. If you need to dive for them you can obviously make a weighted quadrat by filling pvc pipe with sand and gluing it together. Then take an area ...


2

Fish are ectothermic, and so, by definition, cannot hibernate because they cannot actively down-regulate their body temperature or their metabolic rate. However, they can experience decreased metabolic rates associated with colder environments and/or low oxygen availability (hypoxia) and can experience dormancy. For example, epaulette sharks have been known ...


2

How about marine reptiles? Sea snakes have a paddle-like tail, so perhaps you would claim that as a fin, but maybe marine iguanas would qualify? And, of course, sea turtles.


2

This post is pretty well written and seems to say that the evolutionary forces that produce shell color like this is not known. There are suggestions that the color is camoflage or the result of metabolic byproducts or that the pigments serve to strengthen the shell. Its hard to believe some of these theories given that some shells do fine without coloring ...


2

It is more efficient to use fins than feet, hooves, or other similar body parts. It is the same reason that you can swim faster while wearing flippers. Having a larger surface area allows animals to push against more water, so that they have more force when swimming. Here is a picture of the bones in a dolphin fin. They are extremely similar to the bones in ...


2

Some wires crossed here. Most algae are C3, in other words they use the Calvin cycle to fix CO₂. Another way of saying it is that RUBISCO (Ribulose bisphosphate carboxylase) is dorectly responsible for CO₂ fixation. There is some evidence (disputed) that some diatoms use a form of the C4 pathway in which CO₂ is initially fixed as a 4-carbon compound ...


2

This method is commonly practiced. Atleast I see the people working with zebrafish transgenics using it. When you shear the genomic DNA or do a restriction digestion, you are likely to get fragments of different sizes. It is highly probable that the two (or more) locations harboring a copy of the DNA element are a part of fragments with different sizes. So ...


2

Alexander's advice is excellent in the general case, but since I faced a very similar problem when I applied to grad schools last year, I wanted to offer my perspective on this specific union of fields. Many people (including me) believe that this intersection is about to be a really important field - ecologists are starting to recognize the need for ...


2

According to the MarineBio conservation society, the fastest marine mammal is the Common Dolphin, with a top speed of 64 km/h. That places it just above the Zebra on the Wikipedia list of fastest mammals. (I wasn't able to find a primary source for this immediately, so take it with a pinch of salt.)


2

The reason why the cuttlefish is colour blind is because it just has one type of cone cell. Humans have three different types, each sensitive to a different color of light. With only one cone type, you couldn’t differentiate between different colors (reference). A study was conducted in the lab of Dr Lydia M. Mäthger where two different ...


2

Ages of shell as a piece can be checked or counted. Procedure: 1) Examine the shell's ridges with a magnifying glass. 2) Tabulate the number of ridges. You can approximate by number of cell per unit length. 3) Divide the total number of ridges by 365. Each day the little insect earns a new ridge, thus total will give you its age. But, that is age of ...


2

From what I can tell, marine mammals can't dynamically control buoyancy during a dive. They ease the beginning of the dive by starting with a small lung volume to reduce buoyancy. Pinnipeds like seals do this by exhaling half their breath before diving. Deep-diving whales actually breathe in before diving, but their lungs are small relative to body size ...



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