GEOL 388: Field Natural History of the Galápagos Islands

Summer Semester I 2006
The Community of Marine Organisms

Many differences between land and sea in general:

Marine realm can be divided into many different divisions:

Marine organisms life habits:

In Galápagos, we will primarily see Intertidal community, Shallow Sublittoral community, and Shallow Pelagic organisms.

Intertidal Community of the Galápagos

Bases of intertidal community are phytoplankton and algae (a life habit, not a clade!). Most conspicuous is a green alga Ulva lobata (sea lettuce): main food of marine iguanas. Also abundant are various red algae and brown algae.

Benthic suspension feeders:

Benthic suspension feeders in the intertidal zone need to be able to retract their feeding organs (and other tissue) inside a durable watertight covering for that period if time in which they are exposed.

Benthic grazers (a marine "grazer" is an animal that eats sessile organisms, which might be algae or sessile animals):

Sediment feeders, most importantly sea cucumbers (holothuroids), including pepinos (local name for Stichopus fuscus)

Nearshore predators include:

Shallow Sublittoral Community of the Galápagos
Nearshore nektonic organisms, and those that prey on them (note that some of these also include the nektonic component of the intertidal community):

Shallow Pelagic Community of the Galápagos
We will see some marine life out at sea cruising between islands. In fact, we have a better chance of seeing large fish and marine mammals in the archipelago than if we were 100 km farther east: the shallow pelagic realm is generally very sparsely inhabited except where upwelling or other disturbance brings a lot of nutrients up to the photic zone. While out in the open seas, we might see:

Last modified: 18 June 2008