Marine Life OCN 150

Announcements

Exam Key Posting

  • The exam key for the last exam will be posted on Friday. Students should review the key to understand their performance and identify areas for improvement.

Grade Updates

  • Grades will begin to be posted; however, individual scores will not be available just yet. They are anticipated to be finalized and accessible by the end of the day.

Final Exam (Exam 4)

  • The final exam is scheduled for December 126. Please note this is a change from the previously stated syllabus date.

  • This exam will not be cumulative and will specifically focus on materials covered in chapters 12 through 16.

  • The exam is set to start at 8:00 AM instead of the previously mentioned 9:00 AM, so students should plan accordingly to ensure punctuality.

Exam 4 Review

  • Students are encouraged to review the climate slides discussed in class previously and must be familiar with the concepts presented. This review is crucial for understanding the key elements that will be tested.

  • An opportunity will be provided for students to ask questions related to the material before the final exam, ensuring clarity and comprehension.

Introduction to Marine Life

Transitioning Focus

  • The course is shifting focus towards the study of marine life and its classification, emphasizing the fascinating diversity of organisms in oceanic environments. The study will begin with broad categorizations to understand various life forms found in marine ecosystems.

Definition of Life

Key Characteristics:

  1. Energy Dynamics: Living organisms possess the ability to capture, store, and transmit energy. This can be exemplified by the process of obtaining food to utilize energy for growth and maintenance of bodily functions.

  2. Reproductive Capability: All life forms possess mechanisms to reproduce, enabling the continuation of their species.

  3. Adaptability: Life forms exhibit the capacity to adapt to environmental changes, such as behavioral changes like wearing coats in cold conditions.

  4. Atomic Composition: All living organisms are composed of atoms, underlying their biological processes and structures.

  5. Energy Consumption for Order Maintenance: Life consumes energy to maintain order and counteract the natural tendency towards disorder, adhering to the laws of thermodynamics.

Three Domains of Life

  1. Bacteria: Simple, non-nucleated organisms that are crucial for various ecological processes like decomposition.

  2. Archaea: Microscopic life forms that often thrive in extreme environments, playing key roles in biogeochemical cycles.

  3. Eukaryota: Complex multicellular organisms, which include a variety of life such as humans, plants, fungi, and protists, characterized by having a nucleus in their cells.

Classification of Marine Organisms

Marine organisms are classified into three main groups:

  • Plankton: Drifters that cannot move independently and are integral to the marine food web.

  • Nekton: Organisms that have the ability to swim and propel themselves through water, capable of traveling significant distances.

  • Benthos: Organisms residing on, above, or below the sea floor, contributing to the ecosystem's biodiversity.

Plankton

Description:

  • Plankton are unable to swim against currents; they serve as critical components of the marine food chain, providing food for various marine creatures.

Subcategories:

  • Phytoplankton: These are photosynthetic organisms, classified as autotrophs, capable of producing their own food via sunlight.

  • Zooplankton: These non-photosynthetic organisms are categorized as heterotrophs, feeding on other organisms.

  • Bacterioplankton: Microscopic bacteria that play a significant role in marine ecosystems, contributing notably to ocean biomass.

  • Virioplankton: Viruses found in the ocean, impacting plankton populations and maintaining ecological balance.

Lifecycle Classification:

  • Holoplankton: Spend their entire life cycle as plankton.

  • Meroplankton: Have planktonic stages in early life before developing into adults, as seen in species like squid and fish.

Nekton

  • Description: Nektonic organisms possess the ability for active swimming and independent movement in the water column. Common examples include various fish species and marine mammals like sharks and whales that navigate vast ocean spaces seeking food.

Benthos

  • Description: These organisms inhabit or live on the seafloor and can be categorized further as:

    • Epiobenthic fauna: Living on the surface of the sea floor, contributing to surface ecology.

    • Infauna: Organisms that dwell within the sediment, playing vital roles in nutrient cycling.

Marine Life Adaptations

Environmental Challenges:

  • Marine organisms face numerous challenges, including darkness, extreme pressure, and low temperatures found in deep-sea environments.

Hydrothermal Vents:

  • These are unique ecosystems where mineral-rich water is heated, creating oases of life that are rich in biodiversity and distinct from surrounding waters.

Adaptations for Survival:

  • Gills: Adapted to extract dissolved oxygen from water, allowing for respiration in aquatic environments.

  • Body Composition: Varies among organisms based on the habitats they occupy, leading to adaptations that maintain appropriate buoyancy and structural support.

  • Reproductive Methods: Various reproductive strategies exist, such as external spawning that occurs in sync with environmental cues (e.g., lunar phases).

Major Ecological Zones in the Ocean

  1. Coastal Zone: This zone experiences higher temperature variations and is marked by proximity to land areas influencing the ecological dynamics.

  2. Open Ocean: Divided into distinct regions:

    • Photic Zone: This sunlit area supports photosynthesis, containing the majority of marine life.

    • Aphotic Zone: The dark area below the photic zone, where light does not penetrate, supporting different types of organisms adapted to these conditions.

    • Benthic Zone: The sea floor area with diverse organisms that vary greatly in structure and function.

Marine Biodiversity

Distribution:

  • Of the approximately 18 million species estimated on Earth, about 87% inhabit terrestrial environments while around 13% are in marine habitats.

  • Greater species diversity is typically found in the benthic zone compared to the pelagic zone, due to complex structures and interactions at the sea floor.

  • According to the 2010 Census of Marine Life, over 1000 new marine species were discovered, showcasing the vast and unexplored biodiversity of the oceans. Notable examples include unique organisms like the 'Yeti crab', which have extraordinary adaptations to their environment.

Salinity and Temperature Adaptations:

  • Salinity levels play a crucial role in organism distribution, particularly in estuaries that are influenced by freshwater runoff from land.

  • Marine organisms develop various adaptation strategies based on both salinity and temperature fluctuations within their habitats.

Conclusion

The comprehensive study of marine life not only emphasizes the various adaptation mechanisms organisms employ to thrive in diverse aquatic environments but also highlights their ecological significance within marine ecosystems, reminding us of the interconnectedness of life on our planet.