Fish Identification: Dolphins (Part I)

I thought we'd do something a little different today. Everyone is familiar with dolphins in some shape or form, but did you know there are 18 genera (plural of genus) of oceanic dolphins? We are going to cover some of the more common ones. Then you can look smart when someone shouts "Dolphin!" and say, "More specifically, that's a Pacific white-sided dolphin."

Common Dolphin

Common dolphin

It's called the common dolphin, but is probably not the most familiar. There are over 20 species of common dolphin, in all shapes, sizes, and colors. Generally speaking, the common dolphin has a dark back with a white underbelly. Two of the most common variety are the long-beaked and short-beaked. These, like many dolphins, are found in pods of 10-50.

Bottlenose dolphin

Bottlenose Dolphin
If a dolphin should come to mind when you hear "common dolphin", it should actually be the bottlenose. This is the dolphin of pop culture (Flipper) and seen in marine parks worldwide. These are the one of the larger types of dolphin, and are seen the world over, everywhere except in polar waters.

They have a short, well-formed snout that resembles an old-fashioned bottle. They tend to be grey all over, with slightly lighter bellies. Bottlenose dolphins also have more neck flexibility than other dolphins, making them capable of all the expressions that they have become well-known for.

Right whale dolphin

Right Whale Dolphin
Right whale dolphins are predominantly black with small white underbellies. They are distinguished as being one of the only dolphins without dorsal fins.

Right whale dolphins tend to remain in the colder aquatic regions, although they have been spotted in warmer waters. They are divided into species of northern right whale dolphins and southern right whale dolphins. They can be distinguished based on their white patterns: southern right whale dolphins have white that extends further on their body, including their snout and flippers. If still unsure, you should also be able to tell the difference based on where you are in the world.

Killer whale

Killer Whale
The killer whale, or orca, is actually a dolphin. Not surprisingly, it is the largest oceanic dolphin. Killer whales are apex predators, and thus have no natural predators.

Killer whales probably need no description, but they have black backs, white chests and sides, and a white patch above their eyes. They range in size from 5-8 meters (16-27 feet).

There's probably not much you haven't heard about this group, so here's an interesting tidbit. To travel faster, killer whales will leap out of the water while swimming. This technique is called porpoising.

Next time we'll get into the more obscure dolphins.

Common dolphin photo by mikebaird
Bottlenose dolphin photo by The Pug Father
Killer whale photo by [*christopher*][]


Good Underwater Photography: A Key Ingredient

Underwater photography
So often in our haste to take pictures underwater we forget an important fact: to be a good underwater photographer, you first have to be a good diver. The good news, however, is that being an aspiring photographer doesn't have to interfere with your development as a competent diver. In fact, it often accelerates it.

Many of the skills we develop in life are born out of necessity. Likewise, mastery of fin pivots, for example, may come out of the need to get in close to a photo subject rather than rote repetition. The ability to hover effortlessly may arise …


Ear Dryer

Ear Dryer
I randomly came across this interesting device. It's an ear dryer, for drying out the insides of your ears after swimming or scuba diving. It even warms the air it blows into your ear canal.

I was a little surprised to see this device selling for \$100 USD. Who would pay that much for this, especially when you can make homemade swimmer's ear for a couple of bucks?

I started reading the comments on the sales page and it hit me. If you suffer from chronic ear infections, then anytime you come out of the water you are potentially facing …


Why Do We Feel the Urge to Breathe?

This is an interesting tidbit about human physiology, although it applies more to free-diving than scuba.

Free-diving
Try this out: take a breath and try to hold it. Unless you practice this sort of thing, it won't take long before you feel the urge to breathe, that tugging in your chest. Where does that feeling come from?

Most people would guess that your body needs oxygen, and that it translates this need into a physical response urging you to breathe. This is close, but not correct. In fact, this reflex comes from the other half of the same cycle.

Breathing is …


Fish Identification: Longhorn Cowfish

Most fish identification articles here have been admittedly focused on Caribbean creature. I'll try to balance it out in the future, starting today with the longhorn cowfish.

Physical description

[Longhorn cowfish][]
Longhorn cowfish can grow up to 20 inches (50 cm) in length. A member of the trunkfish family, they are characterized by their distinctive box-shaped body. In addition, the long, forward protruding "horns" on the front of their body give these fish their name.

Their bodies are yellow and covered with small white spots all over. Their fins are made of translucent rays, and include dorsal, anal, and caudal. They have …


Mammalian Dive Reflex


Have you ever heard of this? The mammalian dive reflex is a reaction in your body to cold water that allows you to stay underwater longer. It is used extensively by aquatic mammals, like otters, dolphins, and seals. It is also observed in animals like penguins and, of course, humans.

In humans, the water has to be colder than 21 C / 70 F, and it has to be in contact with the face. The sensitives nerves in our nasal cavity are responsible for relaying this information to our brain. When this happens, up to three things can occur:

  1. Your heart …

Don't Make Me Wait

Nobody likes waiting, and they especially don't like people who make them wait. Don't be that person!

When diving from a boat, make sure you are completely ready before moving to the platform. Dawdling on the edge of the boat is highly inconsiderate for those jumping in after you, the crew helping divers off the boat, and your buddy waiting in the water. It's also dangerous, since a jolt to the boat could toss you overboard.

Before moving to enter the water, check that you have done everything to be ready, including

  • Complete buddy check
  • Mask defogged
  • Mask strap adjusted …

Classifying Fish

With over 28,000 individual species of fish (and the number keeps growing), it would take about 540 years for the fish identification series to cover them all.

Fortunately, we don't have to do that. Using some common sense, we can get that number down to something reasonable. First, we can limit based on fish we may actually encounter while scuba diving. With this filter, the number drops to around 4,000. This is still too many, but much closer to being manageable.

Second, we can combine fish that are nearly the same. For instance, it is not critical to …


The Cayman Islands Competition

Grand Cayman Island
You may have seen this floating around the web, but The Cayman Islands are holding a contest for a 7-night stay for two people at a resort, along with airfare!

To enter the contest, you must become a fan of The Cayman Islands Facebook page, and in 100 words or less describe your perfect day on The Cayman Islands.

The contest ends June 24, so you have about a month. I've never been to The Cayman Islands, but I'm sure they're quite a popular destination for a reason. Given the small time commitment, there's no harm entering the contest. Who …


Top Five Places to Dive Before I Die

Duane over at Precision Diving posted an article a few weeks ago on the top 5 places to dive before you dive---I thought I'd play along.

Most of my scuba diving experience has been around the Caribbean, so I tried to balance my list to not be entirely comprised of south Pacific destinations.

  1. Tonga - Reading Tony Wu's Underwater Photography Blog has given me Tonga fever. Sprawling islands with many dive sites, some untouched, makes this a diving paradise. I'd love to spend 1-2 weeks on a live-aboard out that way.
  2. Thailand - Phuket, Ko Samui, Ko Tao, and many other …