Biology Taxonomy and Plankton Overview

Taxonomic Hierarchy

• The taxonomic hierarchy is a system of classifying organisms into increasingly specific groups.
• It begins with the broadest category (domain) and progresses to the most specific (species).
• Examples of categories include domain, kingdom, phylum, class, order, family, genus, and species.

Binomial System

• The binomial system names species using two parts:
  • The first part is capitalized.
  • The second part is not.
• This system ensures that every living thing has a unique name.

Dichotomous Keys

• Dichotomous keys are used to identify species.
• They use a series of paired descriptions that lead the user to a specific organism.
• One pair of options is presented at each step, leading to further choices.

Plankton

• Plankton are microscopic organisms.
• They have limited motility and drift in water currents.
• Main groups are phytoplankton and zooplankton.
• Phytoplankton absorb nutrients from their environment and obtain their nutrition via photosynthesis. Examples include diatoms and dinoflagellates.
• Zooplankton are consumers, such as copepods, which are herbivores feeding throughout their life cycle. Other are meroplankton, abundant during larval stage only (e.g. jellyfish).

Echinoderms

• Echinoderms include starfish, sea urchins, and sea cucumbers.
• They possess an important role in the marine ecosystem acting as keystone species (e.g., sea otters).
• Sea cucumbers burrow in sediments helping oxygenate waste.

Crustaceans

• Crustaceans include crabs, krill, shrimp, and lobsters.
• They possess a carapace (exoskeleton).
• They have jointed legs and two antennae.
• Many crustaceans play important roles in marine ecosystems, including serving as food sources or scavengers.

Bony Fish

• Bony fish have a bony skeleton, operculum (gill cover), gills, and lateral line.
• Gills have a large surface area for gas exchange.
• Lateral lines act as sensors to detect vibrations in the water.
• Swim bladders help with buoyancy.

Cartilaginous Fish

• Cartilaginous fish have a cartilaginous skeleton, gill slits, and no operculum.
• Some examples are sharks and rays.
• They are important consumers and top predators in ocean ecosystems.

Macroalgae

• Macroalgae, such as kelp, are large seaweed-like organisms that grow upright and attach to rocks in marine environments.
• They play an essential role in marine ecosystems as a source of food and habitat.
• They absorb and store large amounts of carbon dioxide from the atmosphere.

Seagrasses

• Seagrasses are marine plants that grow in shallow coastal waters.
• They have roots, rhizomes, and leaves.
• Seagrasses support various marine organisms, including fish, invertebrates, and other plants.