The offshore waters are in reality a living soup and the sea bottom in many places is a richly alive, often densely populated region where almost every square centimetre of surface is occupied by living creatures. In fact, space is such a premium in some localized areas, that many organisms live directly upon the bodies of other creatures. The seashore between high and low tide is known as the littoral or intertidal zone. The water-filled three dimensional space between the surface and the sea bottom is known as the pelagic zone and the sea bottom itself makes up the benthic zone. The minute organisms of the plankton are at the mercy of ocean currents and waves, at best they can only swim weakly and thus do not have the ability to travel independently of moving water.
Phytoplankton are planktonic algae such as diatoms and dinoflagellates.
Several species of dinoflagellates are the causative agents of red tides, which are brought about by seasonal population explosions of these single-celled organisms. Each cell contains reddish pigments known as carotenoids. Red tides are frequently seen during the summer months colouring large patches of the Peninsula's offshore waters with a deep orange tint. Some species that produce red tides are not poisonous but when they multiply so rapidly they deplete the water of nutrients and oxygen resulting in mass mortality of local fish populations. Other species are extremely poisonous, producing powerful nerve toxins that can accumulate in tissues of filter-feeding shellfish such as mussels.