Green, red and brown algae vary seasonally and differ in role as fish food.

Stromatolites are club-shaped structures formed by a slow buildup of microbial mats trapping ooid sands. These form in high energy channels where migrating sand dunes and chemical precipitation of carbonate cement are dominant seafloor processes.

Stromatolites off NURP's research center on Lee Stocking Island.

Sub taking samples on a deep sea basalt bed off Hawaii.

Any kind of structure on the deep sea floor attracts local mobile species.

Offshore red algae communities serve as egg beds for New England herring.

Golden crab attempts to free a buddy from a crab trap. Geryon

Experimental reefs, or casitas, help determine what factors make the best reefs.

Hake lie near the base of a lost "ghost" lobster trap. Urophycis

Once popular tire reefs may break apart and wash up on beaches.

Artificial reefs can increase productivity of sandy bottoms.

Tagged Graysby grouper inside reef block.

Clam shell bed around a thermal mound in 2800 meters.

Black smoker chimney on Endeavour Ridge spouts super-heated water and chemicals.

Edge of a brine pool, a super salty pond, populated by mussels at 800 meters. Bathymodiolus

Tube worms living at a Gulf of Mexico hydrocarbon seep are 2 meters long. Lamellibranchia

Tube worms at a Pacific hydrothermal vent are related to hydrocarbon seep worms. Riftia pachyptila

Black smoker at a mid-ocean ridge hydrothermal vent.

Hydrothermal vent tubeworms get energy from bacteria that live in their plumes.

Sub samples show temperatures in hydrothermal vents exceed 300 degrees celsius.

Mussels, worms and a spider crab at a hydrocarbon seep community.

Minerals venting from the seafloor, provide chemosynthetic sustenance for bacteria, some of Earth's earliest life,

Spider crabs around vent sites on the Juan de Fuca Ridge.

Tube worms feeding at base of a black smoker chimney hydrothermal vent.

Black smoker chimney and shrimp on the Mid-Atlantic Ridge.

Wire corals and snappers on the slope off Hawaii.

Sea urchin grazing deep hard bottom off Hawaii.

Sea cucumber grazing deep hard bottom off Hawaii.

Basket star curled on deep hard bottom off Hawaii.

Sub manipulator prepares to collect coral specimen on the deep slope off Hawaii.

Although there is little light, deep (>500 ft) reefs off Hawaii are productive.

Yellow gorgonian on deep reef off Hawaii.

Attached species compete for space on deep reef off Hawaii.

Sub grabs a wire coral on limestone bottom off Hawaii. Cirrhipathes

Reef fish, including rosy snappers, occupy a deep limestone reef.

Sea cucumber is colored to look like its rocky habitat.

Crinoids and gooseneck barnacles on a dead sponge, over 5000 ft. off Hawaii. Antedon (crinoid)

Gold coral on pillow lava in over 1000 ft. off Hawaii. Gerardia

Satin sponge on basalt slope, at 5000 ft. deep off Hawaii. Semperella

Isolated tufted corals are common on the deep rocky slope off Hawaii.

Glass sponge between red crinoid stalk and gorgonian on pillow lava off Hawaii. Walteria (sponge), Chrysogorgia (gorgonian)

Blackbellied rosefish and rock crab in 1000 ft. off New Jersey. Helicolenus (fish), Cancer (crab)

Pillow lava rocks on the slope off Hawaii form when magma oozes from below.

Yellow iron oxide comes from hydrothermal vents; white is bacterial mat.

Yellow iron oxide covered lava rock on the flank of Loihi submarine volcano.

Ancient coral reef below 700 meters of water off Hawaii.

Cemented ash and talus at a depth of 755 m off Hawaii.

Inactive hydrothermal chimneys made of iron oxide on Loihi volcano.

Duckbill eel in a sand channel between basalt flows at 780 m depth. Nettastoma

Sponges and crab on a basalt talus slope.