Biology Classification Systems Quiz

Course Overview and Logistics

• BIOL 485 is a course on invertebrate biology, offered in Spring 2025.
• The course instructor is Dr. Amy Moran, who specializes in invertebrate ecological physiology, larval biology, and Antarctic marine biology.
• The course website is www.moranlab.org.

Course Materials and Grading

• No textbook is required.
• Lecture notes and other materials are available on Laulima.
• The lecture grade is 80% based on four exams (20% each), which are not cumulative, except for concepts that carry over.
• The remaining 20% of the grade comes from in-class activities (5 out of 6 are graded, 4% each).
• Students are expected to study for approximately 6 hours per week.

Laboratory Information

• The laboratory will be held in Edmondson 103.
• Laboratory sessions begin on Thursday and Friday (January 16th and 17th) and are scheduled for Thursday/Friday only; no lab is held on Tuesday/Wednesday.
• Students need a lab notebook or drawing tablet, dissecting kit, gloves, and field footwear. Lab footwear is recommended for field trips.

Course Questions

• What are invertebrates, and how did their incredible diversity arise?
• What distinguishes the major invertebrate groups from each other?
• How have different animal types solved life's major challenges?

Course Themes

• Morphological diversity
• Physiology
• Ecology
• Evolution

Biodiversity

• Invertebrates make up approximately 99% of all animals.
• There are approximately 32-35 animal phyla.
• Arthropods represent 84.7% of animal species.
• Molluscs compose 4.8%, chordates 4.1%, and other phyla 6.4% of animal species.
• Over 1.5 million animal species have been described, with an estimated total of over 30 million.

Evidence for Invertebrate Diversity

• Charles Walcott, a paleontologist, discovered a rich fossil bed of ancient invertebrates in 1909, known as the Burgess Shale (in the Canadian Rocky Mountains).
• The estimated age of the Burgess Shale is 510 million years old.
• Many modern animal phyla were found in this fossil bed, supporting the concept of the Cambrian Explosion.

Cambrian Explosion

• The Cambrian Explosion refers to the rapid diversification of animal phyla during the Cambrian period.
• The Burgess Shale provides evidence for this phenomenon.
• Representatives like Anomalocaris, Pikaia, Vetulicolia, and Akadocrinus, are among the organisms found in the fossil bed.

Snowball Earth Hypothesis

• Metazoans are thought to have emerged in oceans after the "snowball earth" event, about 550 million years ago.
• This event involved colonization of many suddenly available habitats, resulting in rapid evolution and diversification.
• Once the niches were filled, evolution of species novelty became less successful.

Classification of Diversity in Western Science

• Carolus Linnaeus (1700s), through his Systema Naturae (1735-1770), described over 9,000 species, developing a hierarchical classification system based on shared characteristics.

Linnaean Levels of Classification

• Kingdom, Phylum, Class, Order, Family, Genus, Species.
• Phylum represents a high level of classification characterized by a unique body plan (bauplan).

Modern Classification

• Modern classification utilizes phylogenetic trees based on shared derived characteristics (synapomorphies) for better organization.

Domains of Life

• Three domains of life (bacteria, archaea, and eukarya) were identified in 1977.

Protista (Protozoa)

• Protozoa are unicellular eukaryotes, genetically and morphologically very diverse.

Choanoflagellata

• Choanoflagellata are collar-bearing flagellates and are considered to be the closest living relatives of animals (the simplest branch of the animal evolutionary tree).

Basic Organism Needs

• Acquire energy
• Respond to the environment
• Reproduce
• Develop
• Maintain homeostasis (steady state)
• Perform cellular respiration
• Exchange gases
• Excrete metabolic waste

Metazoan Tissue Organization

• Cells are organized into tissues (only seen in Eumetazoa, not Parazoa), specialized for different functions and interactions.

Grades of Organization

• Single cells (protists)
• Tissue grade—groups of similar cells performing specific functions, arising in embryonic development.
• Organ grade—tissues are organized into organs specialized for different functions.

Impact of Size on Metazoans

• Size significantly affects how an organism interacts with its environment.
• Larger organisms require more complex structures and systems to support their larger size, including improved circulatory systems and gas exchange.

Gas Exchange Methods

• Diffusion is a slow method of gas exchange often limited to organisms of limited size.
• Large organisms rely on systems with larger surface areas available for faster gas exchange, such as flat shapes in organisms and internal structures like lungs or gills.

Circulatory Systems

• Circulatory systems allow oxygen to be transported effectively to internal tissues in larger organisms.

Oxygen-Carrying Pigments

• Respiratory pigments bind to oxygen, significantly increasing the circulatory system's capacity.
• Hemoglobin, hemerythrin, chlorocruorin, & hemocyanin are examples of respiratory pigments.

Metazoan Development

• Development typically proceeds from a blastula to a gastrula.

Collagen Protein

• Collagen is a significant, shared, derived characteristic of the metazoan branch.

Larval Stages

• Many metazoans experience larval stages in their life history.
• These stages are often microscopic and planktonic.
• Transition from a larval to adult form is important for the progression of the life cycle.