Fish Identification: Porcupinefish

Porcupinefish are always a fun sight on dives. They are sometimes called blowfish.

Physical description

The porcupinefish gets its name from the many long spines located all over the head and body. They are members of the pufferfish family, but should not be confused with pufferfish. The porcupinefish's spines are visible even when they lay flat, whereas they are not usually visible on a pufferfish.

When threatened, the porcupinefish can inhale air or water to inflate its body to over twice the normal size. Additionally, this causes the spines to stand up, making the porcupinefish edible only by large predators.

You are not likely to see an inflated porcupinefish, even if you attempt to chase one. I have heard if you manage to grab one by the tail they will inflate, but we all know that's not a good idea, don't we? I have also heard that inflating is stressful and has an effect on the fish's lifespan.

Porcupinefish are a grayish tan color, with white on the underbelly. They are usually covered with small black spots or splotches.

They can reach up to 36 inches (91 cm) in length. They have large heads which taper off towards the caudal fin. They are also distinguished by their large, round eyes which appear to watch you when swimming by. They also have oval-shaped mouths which are usually open.

Geography and habitat

Porcupinefish are found worldwide in tropical, and sometime temperate, regions.

They live in holes on reefs at pretty much all depths. Usually you will encounter them swimming out above reefs, though.

They tend to be solitary, but occasionally you will see them in small groups. They also tend to move very slowly, although they still swim faster than most scuba divers.


Porcupinefish are known to produce toxins in their organs and on their skin. Nevertheless, they are known to be eaten in some areas. My guess is that the toxin is mild enough to only be dangerous to smaller predators.

Further reading

Florida Museum of Natural History
Shedd Aquarium


Cleaning O-rings

We have a quick tip today about cleaning O-rings.

It can be very easy for dirt and lint to hide on O-rings. The grease practically acts as a magnet, letting dirt easily stick. If you're not careful, a few well-placed pieces could even compromise the seal on your equipment---a costly oversight.

To minimize these chances, try cleaning your O-rings on a white (or light-colored) surface. The white will contrast with (most) dirt, making it easier to identify and remove.

[A dirty o-ringClick to enlarge][]
This picture shows the same O-ring, with lint, on a white surface and a wooden tabletop. While ...

Colors Underwater

One of the first things you notice as a new scuba diver is the surprising lack of color. Discovery Channel specials and magazine layouts have brilliant colors. Where'd they all go?

Don't feel ripped off. The fact is, water absorbs light rapidly. So rapidly, that after only 300 ft (80 m), no visible light remains. This is far deeper than you'll ever go, but this absorption is very important at all depths.

The visible light spectrum can be broken up into the familiar constituent colors (for example, see the too-familiar picture of Newton with a prism). From ...

Fish Identification: Schoolmaster

Usually referred to as a "schoolmaster", this fish is part of the snapper family and could also be referred to as a "schoolmaster snapper."

Physical description

[Schoolmaster snapper][]
Schoolmaster can reach lengths up to 24 inches (60 cm), but are common around 12 inches (35 cm).

Schoolmasters are most often recognized by two attributes. First, they have a sharply pointed snout. Second, they have bright yellow fins, which include caudal, pectoral, pelvic, dorsal, and anal.

Sometimes you will also see light vertical bands along their body, as in the schoolmaster pictured here.

Geography and habitat

Schoolmaster snapper are found all along the ...

More Uses for Old Wetsuits

The other day we talked about cycling wetsuits to give new life to old wetsuits. I briefly mentioned throwing out those super-old wetsuits when they get replaced by old wetsuits.

I was thinking about it, and maybe you don't have to throw them out after all. Here are three ideas to consider before throwing it away:

Old wetsuits

  • "Recycle it." Before throwing it away, consider donating it for recycling. This can be something like Rip Curl's [Project Resurrection][], where old neoprene is recycled, or something like A Warm Current (website currently down), who take old gear for kids.
  • Use it ...

Slack Tide

There's something to be said for shore diving. No boats to wait for, no people to annoy you---you dive when and where you want. Even places you wouldn't expect (like New York and New Jersey) can have decent shore diving.

If you spend any time reading about shore diving, either from books or the internet, you're bound to come across the term slack tide, or sometimes, slack water. Slack tide refers to the time between high and low tides, when the tide is changing. That means there are four a day in most places.

During this time ...

Old Wetsuits

The day will come. Your brand new, off-the-rack wetsuit will one day just not keep you that warm anymore. It's time to buy a new one. Don't feel bad, you got a good 4-5 years of diving out of it; the investment has been well worth it. Besides, a new wetsuit won't set you back that much.

Old Wetsuits
Just one thing remains: what do you do with the old wetsuit? Structurally it's still in decent shape, so it's a shame to throw it away. The good news is there's a reason to hold on to ...

Fish Identification: Spotted Scorpionfish

Today's fish is a member of the infamous scorpionfish family.

Physical description

[Spotted scorpionfish][]
Spotted scorpionfish are large for their family. They average around 12 inches (35 cm) long, with some males reaching 18 in (45 cm) in length.

They have wide, fan-like pectoral fins as well as dorsal spines that make this a formidable looking fish. The fleshy plumes covering their eyes give them the appearance of a grumpy old man.

Spotted scorpionfish usually have a reddish color. Their pectoral fins have a combination of white stripes and spots, hence the name. The tails also have three white stripes.

You ...

Snorkel Length

Snorkels, snorkels everywhere
There are many factors to consider when purchasing a snorkel: shape, mouthpiece, barrel type, valves, and even how well you like the look of it. One factor you may not consider is the length of the snorkel.

Some people might think a longer snorkel is always better. The longer it is, the less chance water will get in, right? While true, there are two other important considerations:

  • Dead air space is a concept that comes up in many different areas of scuba. Dead air is the gas in airways left from the end of your last exhale. It consists of ...

Around the Web

In today's update I'll share a few links from around the internet: has a several post series of Florida Keys dive sites. It certainly has me intrigued enough to get down to the Keys.

Alive2dive gives a rundown of personal gear selection. It's similar to our article on which gear to buy, but check it out for another opinion.

PADI Instructor News gives a breakdown of the new PADI open water prescriptive lesson guides and the new PADI Pro site (which is much better than the old one).

Tony Wu's underwater photography blog has ...