Intro
Table of Contents
Preface
Humans as observers in the sea
Greater abundance of organisms than on land
Snorkelling and diving
This book is a habitat guide...
A few words about the authors
Every time we put on fins and goggles...
Habitat-Defining Parameters
In the sea, just as on dry land, very different habitats exist
Substances can travel very far
Geological, geographical, and climatic parameters
Impact of oceanic forces
Proximity to river mouths
Tropical or temperate
"Keystone species"
A journey along the path of solar energy

Habitats in the Mediterranean Sea
1 Bright, sun-exposed rocky ground
2 Dark, shady rocky ground
3 Sea caves
4 Intertidal zone
5 Sandy ground
6 Seagrass
7 Deep muddy ground
8 Open water
Impressive Photo Models in their Habitats
Habitat: Sunlit Rocky Ground
Durable subtrate
Distinction based on solar irradiance
Sun-loving Brown Algae
The blanket-forming growth of Cystoseira kelp
Seasonal changes
Living off carbohydrate reserves until spring
A chance for peacock's tail and forkweed algae
Other Algae in Shallow Seas

A forest of umbrella algae blanketing the bottom
Giant cell with nucleus at the base of the stalk
A ground-breaking discovery
Fertilised sea lettuce
Every illuminated rock on the sea floor...
Sessile Animals
Anemones
Sea anemones: underwater gardeners
Mediterranean snakelocks sea anemones form a "dinoflagellate garden"
Two colour morphs with identical clone colonies
Protection in the Poisonous Tentacle Forest
Coral Polyps
Coral colonies in the Mediterranean
Pillow corals have their own microalgae garden
Corals with only one polyp
Sun-loving Sponges

Sponges are sessile animals...
The body of a sponge...
Sponges constantly absorb water
Symbiotic blue-green algae
The yellow tube sponge Aplysina...
Excurrent and incurrent openings
Kidney Sponge, Chicken Liver Sponge, Bath Sponge
Kidney sponge: cushion-shaped and slippery smooth
Chicken liver sponge: reproduction through "abseiling"
Bath sponges
Complex cleaning process
Tubeworms
Plankton feeders growing among algae
A complex feeding system
The position of the radioles is optimised
Hydropolyps
waiting for food
Marine Grazers
Mobile animals

The sea hare Aplysia...
Reproduction of sea hares
When Mantel Flaps Become Wings
Purple poison
Cropped Down to the Bare Rock
Purple Sea Urchin and Black Sea Urchin
Light, waves, and warm water
Purple sea urchin (1)
Typical back decoration
The black sea urchin (2) never picks up objects
The Violet Sea Urchin
Renewable teeth
The violet sea urchin Sphaerechinus (3)...
Not every violet sea urchin is a
Easier to distinguish by their shell skeletons
Abalones and Star Shells
Abalones are crepuscular
Leftovers