During the first section we discussed basics of marine science. Now we’ll begin taking a look at marine life and all of it’s diversity.

Find your way home, little extremophiles (Fly beloved sons) Find your way home, donors of life (Fly my chosen ones) You're on your own, little extremophiles (Ride your frozen ark) You're on your own, cleaving the skies (Ride into the dark) Carry out our dangerous task Sail uncharted spheres Live out our dreams, ride the comet Journey on the Migrator trail Cross the new frontiers Pass on our genes, ride the comet You are the future, little extremophiles (Fly towards the sun) You are the future, you know what to do (Fly it has begun) Carry out our dangerous task Sail uncharted spheres Live out our dreams, ride the comet Journey on the Migrator trail Cross the new frontiers Pass on our genes, ride the comet Carry out your dangerous task (Carry on) Sail uncharted spheres (Hey, hey) Live out our dreams Ride the comet (You ride the comet) Journey on the migrator trail (Migrator trail) Cross to new frontiers (Oh yeah) Pass on our genes Ride the comet (Yeah, yeah, yeah, yeah) Courtesy: Arjen Lucassen

The Microbial World

Introduction We begin our survey of ocean life with the smallest of marine organisms, the bacteria and archea. Both groups contain members which are capable of photosynthesis an are known as primary producers. These primary producers are responsible for directly or indirectly feeding most marine organisms.

Whale shark, Rhincodon typus From the largest…

To the smallest… Octopus larvae

Prokaryotes The first organisms we will consider will be the prokaryotes. Prokaryotes are the smallest, simplest (and oldest) organisms around. Unlike other animals we will study, prokaryotes lack a nucleus. Two main categories of prokayotes are Archea and Bacteria

Marine bacteria take on many shapes, including spheres such as Thiomargarita namibiensis, a benthic bacteria which can be seen with the naked eye. Other shapes include rods, rings and spirals. Some may form into large calcium containing mounds (stromatolites). Still others break down organics and cycle nutrients. Stromatolites, Exuma Cays, B.I

Life and Death Perhaps one of the most interesting evolutions of bacteria cocerns the development of bioluminescence and toxins (tetrodotoxin). Whether used as a flashlight fish’s trick for attracting prey, or giving a good buzz to your fugu sushi, bacteria occupy some amazing niches in the marine world!

Cyanobacteria: Red Tide Planktonic spp. such as cyanobacteria (which can cause red tides) often multiply very rapidly. The contain red pigments! Go figure… Red tides (Karenia brevis)-can be caused by dinoflagellates too (photo).

Archaea: Extreme Conditions Archaea are similar to bacteria, but they are able to tolerate conditions most other bacteria wouldn’t be caught dead around... okay, maybe they would be caught dead hear! Some are able to tolerate temperatures near hydrothermal vents (176°F, 80°C). Archaea are similar to bacteria, but they are able to tolerate conditions most other bacteria wouldn’t be caught dead around... okay, maybe they would be caught dead hear! Some are able to tolerate temperatures near hydrothermal vents (176°F, 80°C).

Prokaryotic Metabolism

How do you eat?? Many bacteria (autotrophs) are perfectly capable of feeding themselves, making their own organic compounds by photo- or chemosynthesis. Bacterial photosynthesis can be different than that found in plants (i.e. you might produce S instead of O 2 ). Some autotrophs which produce methane as products are being used to meet our energy needs.

How do you eat (cont.)?? Bacteria which utilize other sources of carbon (organics) to exist are known as heterotrophs. Many heterotrophs are involved in decay processes and some even exist in anoxic (no O 2 ) conditions. Still others are actively fixing nitrogen from gas to molecules which other animals can use as food during primary production.

Unicellular Algae Being composed of one cell isn’t an evolutionary dead end. Alagae, Diatoms, Dinoflagellates, and Radiolarans all have been aound for millions of years (if not billions). Being eukaryotic, unicellular organisms such as these use a variety of methods to eat, metabolize, and reproduce. As a group these organisms are known as Protist!

Diatoms contain many organelles that enable them to exist under potentially harsh conditions. Most diatoms constist of strikingly delicate outter shells of SiO 2 (frustules) which provide limited protection and light penetration.

Diatoms reproduce asexually (cell division) and sexually (auxospore), depending on external conditions.

Dinoflagellate, Gonyaulax polyedra Dinoflagellates exhibit two flagella which permit movement. Groove Theca One flagella is located within the groove and the other is located at the lower end (not visible).

Slilicoflagellates are characterized by star-shaped internal skeletons. Some may be used for aging marine sediments.

Still others, like these Coccolithophorids are surrounded by shells of calcium carbonate (CaCO 3 ) and are responsible for significant primary production! Umbilicosphaera sibogae

Some eukaryotes are more like animals than like plants! In fact, having a single cell is about the only thing that these critters have in common with other eukaryotes we have observed. Foraminiferans and radiolarans utilize specialized pseudopodia (spine-like projections) to capture food.

The outer shell, or test, is made of CaCO 3 and serves as a protective structure.

Ciliates are protozoans which utilize cillia for feeding and in some cases locomotion.

Bahia Fosforescente, Puerto Rico At night this bay is illuminated by Pyrodinium bahamense, a phosphorescent dinoflagellate.