SEA EXAM 2

Lecture 9 - Introduction to Phylogeny: 

  • Classifications of the biological hierarchy: Domain/Kingdom/Phylum/Class/Order/Family/Genus/Species. 

  • 3 Domains of life:  

  • Bacteria: Single-celled prokaryotes. 

  • Archaea: Single-celled prokaryotes. 

  • Eukarya: Everything else. 

  • Phylogenetic tree: Shows evolutionary relationships, branches represent lineage and divergence. 

  • Evolutionary relationships: Determine common ancestors and lineage splits using phylogenetic trees. 

Lecture 10 - Inverts 1: 

  • Taxonomic biological hierarchy: Domain/Kingdom/Phylum/Class/Order/Family/Genus. 

  • Species: Group of organisms capable of interbreeding and producing fertile offspring. 

  • Importance of viruses: Control microbial populations and nutrient cycles. 

  • Marine vs. terrestrial food chains: Marine chains have more trophic levels, rely heavily on plankton. 

  • Animal: Multicellular, eukaryotic organisms that are heterotrophic. 

  • Animal symmetry:  

  • Radial: Central axis (e.g., jellyfish). 

  • Bilateral: Left and right mirror (e.g., humans). 

  • Asymmetrical: No symmetry (e.g., sponges). 

  • Cephalization: Concentration of sensory organs and nerve cells at the front end, enhancing movement and response. 

Lecture 11 - Inverts 2: 

  • Lophotrochozoans: Group characterized by a feeding structure called lophophore and/or a larval stage called a trochophore. 

  • Flatworms: Bilateral symmetry, acoelomate, simple digestive system. 

  • Classes in Phylum Platyhelminthes:  

  • Turbellaria: Free-living, regenerative abilities. 

  • Trematoda: Flukes, live in internal organs, complex life cycles. 

  • Cestoda: Tapeworms, live in intestines. 

  • Monogenea: Ectoparasites, attach to external surfaces. 

  • Feeding:  

  • Turbellarians: Pharynx, through mouth and throat. 

  • Cestodes: Absorb nutrients through their skin. 

  • Life cycle of Schistosoma: Eggs -> Snails -> Humans. 

  • Rotifers: Microscopic, have organs, move using cilia, reproduce sexually or parthenogenetically. 

  • Nemertean proboscis: Used for hunting, everted from a cavity, muscular tube with a stylet. 

  • Sponge anatomy: Simple body plan with pores, canals, and chambers. 

  • Sponge cell types: Choanocytes, Amoebocytes, Pinacocytes. 

  • Sponge organization: Asconoid (simple), Syconoid (folded), Leuconoid (complex). 

  • Spicules: Structural elements made of silica or calcium carbonate. 

  • Cnidarian body plans: Polyp (sessile), Medusa (free-swimming). 

  • Jellyfish vs. sponges: Jellyfish have true tissues (eumetazoans), sponges do not (parazoans). 

  • Jellyfish sting: Cnidocytes contain nematocysts with coiled barbed thread and toxins, triggered by cnidocils. 

  • Schyphozoan lifecycle: Alternates between polyp and medusa stages. 

  • Classes of cnidarians: Hydrozoa, Scyphozoa, Cubozoa, Anthozoa. 

Lecture 12 - Inverts 3: 

  • Mollusc features: Mantle, radula, muscular foot. 

  • Polyplacophoran adaptations: Shell with eight plates, strong foot for clinging to rocks. 

  • Polyplacophoran anatomy: Dorsal shell, ventral foot, radula for feeding. 

  • Gastropod features: Torsion, coiled shell, diverse habitat. 

  • Bivalve anatomy: Two-part shell, filter feeders, no radula. 

  • Cephalopod anatomy: Tentacles, beak, complex eyes. 

  • Cephalopod defenses: Camouflage, ink, fast swimming, intelligence. 

  • Chromatophore: Pigment cell that allows color change. 

  • Mollusc locomotion:  

  • Gastropods: Foot. 

  • Cephalopods: Jet propulsion. 

  • Bivalves: Burrowing. 

  • Mantle modifications:  

  • Bivalves: Shell secretion. 

  • Cephalopods: Siphons. 

  • Polychaete anatomy and locomotion: Segmented bodies, parapodia for movement. 

  • Polychaete types:  

  • Errant: Mobile predators. 

  • Sedentary: Tube-dwellers. 

Lecture 13 - Inverts 4: 

  • Ecdysis: Molting process in arthropods, crabs shed their exoskeleton. 

  • Tardigrade conditions: Moist environments, can survive extreme conditions. 

  • Feeding in nematodes: Use a muscular pharynx to ingest food. 

  • Nematodes as ecdysozoans: They molt their cuticle. 

  • Crustacean features: Exoskeleton, jointed appendages, two pairs of antennae. 

  • Lobsters vs. barnacles: Lobsters are mobile and predatory, barnacles are sessile filter feeders. 

  • Barnacle feeding: Attach to surfaces, use cirri to filter feed. 

  • Skeleton types:  

  • Endoskeleton: Internal. 

  • Exoskeleton: External. 

  • Hydrostatic: Fluid-filled. 

  • Nature’s constraints: Evolutionary trade-offs, environmental changes, genetic constraints. 

Lecture 14 - Coastal Seas: 

  • Sea vs. ocean:  

  • Sea: Smaller, partially enclosed by land, shallower. 

  • Ocean: Larger, not enclosed by land, deeper. 

  • Rocky coast life:  

  • Abiotic factors: Tides, wave action, temperature, salinity, sunlight. 

  • Biotic factors: Predation, competition for space and food. 

  • Rocky coast creatures:  

  • Barnacles: Cement to rocks. 

  • Mussels: Use byssal threads. 

  • Sea stars: Tube feet with suction cups. 

  • Snails: Strong, muscular foot. 

  • Chitons: Flattened bodies, strong foot. 

  • Mangroves:  

  • Locations: Tropical/subtropical regions. 

  • Importance: Protect shorelines, filter pollutants, provide habitat. 

  • Seagrass beds:  

  • Locations: Shallow, salty, and brackish waters. 

  • Importance: Provide habitat, stabilize sediments, support biodiversity. 

  • Coral reefs:  

  • Formation: Coral larvae attach to submerged rocks. 

  • Locations: Warm, shallow ocean waters. 

  • Importance: Biodiversity hotspots, protect shorelines, support fisheries. 

  • Coral bleaching:  

  • Process: Corals expel symbiotic algae due to stress, turn white. 

  • Causes: Temperature changes, pollution, overexposure to sunlight. 

  • Consequences: Loss of biodiversity, weakened coastal protection. 

  • Coral reef importance and perils:  

  • Importance: Support marine life, protect coastlines, support tourism. 

  • Perils: Climate change, pollution, overfishing. 

Lecture 15 - Open Seas: 

  • Pelagic realms:  

  • Epipelagic zone: Surface to 200 meters. 

  • Mesopelagic zone: 200 to 1,000 meters. 

  • Bathypelagic zone: 1,000 to 4,000 meters. 

  • Abyssopelagic zone: 4,000 to 6,000 meters. 

  • Hadopelagic zone: 6,000 meters and deeper. 

  • Depth zone conditions and adaptations:  

  • Epipelagic: Light, warm. Adaptations: streamlined bodies, countershading. 

  • Mesopelagic: Dim light, cool. Adaptations: large eyes, bioluminescence. 

  • Bathypelagic: No light, cold, high pressure. Adaptations: slow metabolism, bioluminescence, large mouths. 

  • Abyssopelagic: Near freezing, high pressure. Adaptations: flexible bodies, reduced skeletons. 

  • Hadopelagic: Extreme pressure, near freezing. Adaptations: specialized enzymes, proteins. 

  • Plankton and nekton:  

  • Meroplankton: Temporary plankton (e.g., larvae of sea stars). 

  • Holoplankton: Permanent plankton (e.g., copepods). 

  • Ichthyoplankton: Fish eggs and larvae. 

  • Nekton: Actively swimming organisms (e.g., fish, squid). 

  • Diel vertical migration: 

  • What: Daily movement from deep to surface waters at night and back during the day. 

  • How: Triggered by light changes, internal clocks. 

  • Participants: Zooplankton, small fish, squid. 

  • Importance: Avoid predators, access food, carbon cycling. 

  • Feeding on dispersed prey: 

  • Filter feeding: Straining small particles (e.g., baleen whales). 

  • Ambush predation: Lying in wait (e.g., anglerfish). 

  • Active hunting: Pursuing prey (e.g., sharks). 

  • Scavenging: Feeding on dead organisms (e.g., hagfish). 

  • Sargasso Sea: 

  • Location: North Atlantic Ocean, bounded by currents. 

  • Importance: Habitat for marine life, nursery for fish and turtles, supports endangered species, carbon sequestration.