29 Oct 2009

Intertidal hermit crab.

Clibanarius erythropus is famous for a variety of reasons such as his funny name, the big range of shells and his usage as a bait. The last reason happens because it is very easy to trap him in the rockpools where it uses to sit. It has a foraging behavior and it selects substrates where there are a lot of filamentous algae and corticated macrophytes to eat. It moves big distances per day and research showed that the type of shell that it uses influences the extent of movement. In the video you can watch a strange meeting of hundreds of hermit crabs under a rock. Probably this happens for the reproduction. I made it in very shallow water (o,5m).

28 Oct 2009

The fish of the eerie heavens!

There is a myth that says that this fish was given to Jesus by St. Peter, the gatekeeper of heaven. The false eye mark on each side is said to be from St. Peters fingers. I can see why he would do that as this fish, besides it's majestic appearance, the John dory is one of the most delicious fish in the sea. It can reach 20 kg and is mostly solitary but on this reef in Nikiti they are spotted in pairs.. His massive, protrusible mouth catches schooling fish and is quite remarkable to see, hopefully here, very soon!
To see them visit the You tube Medisea channel, Poseidon Diving School or any dive centre near you..just say your prayers before :p

22 Oct 2009

Greater Mediterranean hermit crabs

As most species of crabs Greater Mediterranean hermit crabs are susceptible to fights. Here you can admire the impact of Mike Tyson to the animal kingdom. (Video by Kostas Milonakis, unidentified if they are D.arrosor or D.calidus)

Dardanus calidus with some Calliactis parasitica on his shell.

Dardanus calidus

When you diving at Mediterranean you can meet two species of Big Hermit crabs (Bernard-l'ermites). The species Dardanus arrosor and Dardanus calidus can grow more than 6cm and both can be symbiotic with the anemone Calliactis parasitica. Unlike with the parasitic symbiosis that this anemone has with the Atlantic Hermit crab Pagurus bernhardus it is confirmed that D.arrosor assists the trasfer of C.parasitica to its shell. Also the same experiments showed that most of the D.arrosor that had accepted C.parasitica to their shell were females and males prefer to be on their own.

21 Oct 2009

Posidonia fragile heaven

The Posidonia meadows are a key marine coastal ecosystem for the Mediterranean. These flowering plants are the longest living organism of our seas, with a growth rate of 1 cm per year! In this picture we can see some of the hundreds of plant and animal species that live and breed within the meadows. This particular meadow is in Nikiti on a reef 2 miles offshore. Because the top of the reef is very shallow, no commercial fishermen fish on it, but around it, allowing the roots of the plant to be covered by very delicate species of bryozoans and red coralline algae. A bit further along a small Octopus vulgaris was finding refuge in the jungle of seaweed!
This is the beauty of unspoiled and undisturbed Posidonia oceanica meadows, protecting them is as vital as the sea is to the planet.

19 Oct 2009

The dream team!

The list that follows shows the Sharks species of Mediterranean (Superorder Selachimorpha) and their IUCN Red list status.
1)Heptranchias perlo Near Threatened
2)Hexanchus griseus Lower Risk Near Threatened
3)Hexanchus nakamurai Not evaluated
4)Echinorhinus brucus Data Deficient
5)Squalus acanthias Vulnerable
6)Squalus blainville Not evaluated
7)Centrophorus granulosus Vulnerable
8)Squalus uyato Not evaluated
9)Etmopterus spinax Not evaluated
10)Centroscymnus coelolepi Near Threatened
11)Somniosus rostratus Not evaluated
12)Oxynotus centrina Vulnerable
13)Dalatias licha Data Deficient
14)Squatina aculeata Critically endangered
15)Squatina oculata Critically endangered
16)Squatina squatina Critically endangered
17)Carcharias Taurus Vulnerable
18)Odontaspis ferox Data Deficient
19)Alopias supercilious Not evaluated
20)Alopias vulpinus Data Deficient
21)Cetorhinus maximus Vulnerable
22)Carcharodon carcharias Vulnerable
23)Isurus oxyrinchus Lower Risk Near Threatened
24)Isurus paucus Vulnerable
25)Lamna nasus Vulnerable
26)Scyliorhinus stellaris Not evaluated
27)Scyliorhinus canicula Not evaluated
28)Galeus atlanticus Near Threatened
29)Galeus melastomus Not evaluated
30)Galeorhinus galeus Vulnerable
31)Mustelus asterias Lower Risk Least Concern
32)Mustelus mustelus Lower Risk Least Concern
33)Mustelus punctulatus Not evaluated
34)Carcharhinus altimus Not evaluated
35)Carcharhinus brachyurus Near Threatened
36)Carcharhinus brevipinna Lower Risk Near Threatened
37)Carcharhinus falciformis Lower Risk Least Concern
38)Carcharhinus limbatus Lower Risk Near Threatened
39)Carcharhinus melanopterus Lower Risk Near Threatened
40)Carcharhinus obscurus Lower Risk Near Threatened
41)Carcharhinus plumbeus Lower Risk Near Threatened
42)Carcharhinus longimanus Vulnerable
43)Prionace glauca Lower Risk Near Threatened
44)Sphyrna lewini Lower Risk Near Threatened
45)Sphyrna zygaena Lower Risk Near Threatened
46)Sphyrna tudes Vulnerable
47)Sphyrna mokarran Endangered
48)Pristis pectinata Critically endangered
49)Pristis pristis Critically endangered

12 Oct 2009

Octopus - the magnificent 8

Everyone who visits the Greek islands is familiar with the picture of the hanging bodies of the octopus. Famous for his tasteful meat octopus is the most popular food for the summer. Fortunately the population of the octopus doesn’t seem to be endangered because of the fishing. If it lives in good conditions with plenty of food can grow up to 10kgr extremely fast. It is very famous for his skills and abilities that make it one of the most impressive marine animals and a very good hunter. During the day he hunts near his nest but on the other hand in the night makes long walks searching for food (video) It can camouflaged near the rocks and burry himself in the sand (photo) in order to do ambush his victims. Also it seems to be very clever as it can open cans and glass jars if it wants to take the containment. It has been proven that it can learn and remember tricks for a long time. Octopuses are territorial animals and usually in the area you will find individuals of the same size. Some of them are very good builders and make a well style nest using rocks over the sand. They also use rocks to block the entrance of the nest (video). When the octopus is afraid it makes a red and white coloration ring around his eyes and ejects ink (photo).

A night excursion! filmed by Michalis Adamtziloglou

An octopus trying to mime the color of the sand

Burried alive to ambuscade the enemies.

Reproduction time, one of the male tentacles has the hectocotylus which is the tentacle that carries the spermatophores. The female gametes are inside the mantle. These two animals seem to be afraid of each other.

Ejecting ink to have more time to run and hide.

A well style nest.

Octopus uses rocks to hide and block the entrance of the his nest.

After mating come the eggs some species can lay up to 500.000 eggs. The female guards the strings of eggs for about a month. She is a very caring mother!, this time however she left her nest for a little sea stroll.

Octopus is a usual issue for ancient Greek amphoras (this from the Minoan civilazation)

Octopus also can be protagonist or inspire some very funny situations

11 Oct 2009

Have you hugged a shark today?

Shark week has started, from the 10th until the 18th of October, people across Europe are speaking out for sharks.
The top predator of our seas has been around before the dinosaurs, but sadly now some species like the Basking Shark (Cetorhinus maximus, not dangerous) are in danger of extinction.
A new report by the IUCN shows that 40% of the shark species in the Med, are threatened by extinction, making this Basin the most dangerous place if you are a shark. For many species there is insufficient data about their populations.
In Greece the lack of ANY data could possibly mean that some have disappeared without us ever knowing.
Sharks and rays are, for me, the most impressive marine life that I have encountered so far, and none of my interactions have been menacing, although I was lucky enough to see some of the more dangerous species. Until now the only sharks I have seen in Greece, have been dead, or alive and then brutally murdered just because it was a shark and it deserved to die, as it is "dangerous". This picture was from one such occurrence in Paros, Greece (photos by Makis Terzis), of a Thresher Shark (not dangerous, unless provoked). He came out to the shallows where the people hauled him on shore and cut him up.
The depletion of sharks from our seas may cause unpredictable changes in the ecosystem, including loss of biodiversity and probable depletion of other fish stocks.
If you care even slightly about the future of our seas, please don't consume any shark products and inform yourself on the matter, sharks are NOT the stereotype you know.
"Have you hugged a shark today?" is a metaphorical statement!
sharks may be dangerous and unpredictable, do not attempt to hug or touch them ;)
Just respect and protect them.

In the Greek language we call this fish alepou (αλεπού της θάλασσας) which means fox. This word, alepou, gave its name to the family, Alopiidae.

8 Oct 2009

The coat-of-mail shells (aka chitons)

Chitons is the common name for the species of the Polyplacophora (Class) shells. Polyplacophora is seems to mean at Greek "the ones who have a lot of plates". The shell is composed from a lot of plates so the animal is more flexible to his movement. The first photo is from Chiton olivaceus which probably take his name from his colour which is similar to the olive. The second photo is the specie Lepidopleurus cajetanus and the photo taken as I moved a rock at shallow water. Both pictures was taken at Paros island in shallow water. More information about Chitons behaviour you can find in the following link.

Chitons: Polyplacophora - Behavior And Reproduction