Join me in the cold, dark, life-sustaining NE Pacific Ocean to discover the great beauty, mystery and fragility hidden there.

Posts tagged ‘biodiversity’

Come Away With Me

Come on. You know you want to, just for 3 minutes.

Come on the dives I did today.

The little slide show I have put together, is a testimony to the grand, jaw-dropping biodiversity of this area (Northern Vancouver Island, B,C., CANADA).

The Minke whale we saw, the fish using a sponge as a hammock, the bald eagle chick that took one of its first flights – all these are animals that I have learned from by knowing a small part of the world’s ocean well enough to be able to recognize individual animals.

Such a privilege and such a joy to share with you.

Come away with me . . . . click here.

Sea Spiders?!

Yes – there are spider-like animals in the ocean!

Globally, more than 1,300 species have been identified.

Yellow Hairy Sea Spider grazing on the polyps of Red Soft Coral. ©Jackie Hildering.

But, even though they are jointed-legged invertebrates (arthropods) and most do have 8 legs, they are not true spiders (arachnids) nor are they crustaceans. They are classified into the a distinct group of arthropods ( the chelicerate subphylum). The name of the order to which this species belongs to is the “pantapoda” which is Latin for “all legs”, a good label as they have almost no abdomen. 

“All legs” indeed. ©Jackie Hildering.


T
hey have a mouth part called a proboscis, a flexible tube that they use to mix digestive chemicals with their food and then suck it up.

Yellow Hairy Sea Spider having grazed off polyps of Red Soft Coral. Also appears to have “decorated” himself with algae. ©Jackie Hildering.

Some species have additional leg-like appendages near their mouths. Often only the male has these structures so that they can take care of the eggs by carrying them.

The species pictured here are those I see most often around NE Vancouver Island and they are only about 1 cm across. They have been given the common name “Yellow Hairy Sea Spider” (Tanystylum anthomasti).  The hairy parts are believed to help the animals feel and sense chemicals.

Yellow Hairy Sea Spiders  grazing on Red Soft Coral. ©Jackie Hildering

I have only ever seen this sea spider species on Red Soft Coral colonies (Gersimia rubiformis). As you can see in the photos, they feed (graze) on the bushy polyps of the soft coral. As defence, the polyps can retract and have stinging cells but this seems to do little to deter the sea spiders. 

One of the things I find fascinating about sea spiders is that they have a very thin external skeleton (exoskeleton) and as a result don’t need a respiratory system; they can “breath” through their skins.

Nudibranch species that also feed on Red Soft Coral include the Diamondback Nudibranch (Tritonia festiva to 10 cm) and the Orange Peel Nudibranch (Tochuina gigantea to 30 cm). See below. 

 

Sources:

Below the Kelp

It’s the day before summer begins and  . . . what a day it was.

We had radiant sunshine and a flat-calm ocean during our dive today.

I can think of no better way to share the beauty and wonder of today’s adventure than to take you below the kelp with me.

Please see today’s images at link below. I have included captions that provide a bit of information about the species we were so fortunate to see.

Come below the kelp – by clicking here.

One Dive – Photographic Essay

Swimming anemone at Stubbs Island, N. Vancouver Island, BC

Today there was quite a small tidal exchange which allowed us to dive a more challenging site, Stubbs Island.

On larger tides, this island receives so much current that eddies and big upwellings form. All this churning water means there is abundant oxygen and plankton delivery so the density of marine-life on Stubbs Island is truly mind-blowing.  There isn’t a centimetre of rock that does not have something growing on it.

I would like to share my images from this dive today. I hope they give a sense of the awe-inspiring beauty and biodiversity of our Northern Vancouver Island marine “backyard”.

I’ll let the photos do talking.

Click here for the photos of  –  just one dive at Stubbs Island.

Challenge – Find the Crab!

 

 

Typical shape of members of the kelp crab family. Species in this family are usually from 5 to 9 cm across the carapace.

This week I bring you the “Where’s Waldo?” of the marine invertebrates. There is a decorator crab in each of the images at the link below. But first, here are some clues for you.

Most of the species of crabs that decorate themselves to be masters of camouflage are in the spider crab family (Majidae family – also known as “kelp crabs”).  The image to the right shows you an undecorated kelp crab with the typical long legs and distinctly shaped shell (“carapace”) of this family.

Some crabs only partially camouflage themselves, especially when they are juveniles. Others “plant” so many marine neighbours onto themselves that you can’t tell them apart from their environment until they move.

Although they look like walking gardens, the organisms they attach to the stiff, curved hairs on their legs and backs are algae and animals, not plants. The animals can be soft corals, sponges or unique creatures like “bryozoans” and “hydroids”.

Not only does this covering of life allow the crabs to hide from predators, it also changes the way the crabs feel and taste. For example, sponges taste bad or are even toxic to many predators so, if you cover yourself with sponges, predators be gone! The bonus of carrying other organisms on your back is that you also have a food supply within a pincher’s reach.

It is truly astounding how well the decorator crabs match their immediate surroundings which added another mystery to my list: Is the range of decorator crabs really small so that they always match their background OR do they know to “adjust” their camouflage when they move to an area where they no longer blend in?

I have learned that the latter appears to be the case. Experiments with captive decorator crabs have shown that, if moved to a background that no longer offers camouflage, the crabs will “adjust” their decorations!

Click here to find the decorator crabs in my images or view gallery below.