Untitled Quiz

Molluscs (Phylum Mollusca)

• Vary in size, inhabiting marine, freshwater, and terrestrial habitats
• Include herbivores, carnivores, and filter feeders, as well as parasites
• Approximately 100,000 species
• Three main parts: visceral mass (containing internal organs), mantle (covering visceral mass, may secrete calcium carbonate and help develop gills or lungs), and foot (for locomotion, attachment, and food capture)
• Possess a radula for grazing and other feeding methods
• Well-developed nervous system

Molluscs - Bivalves (Class Bivalvia)

• Examples include clams, oysters, mussels, and scallops
• Two parts to the shell, closed by adductor muscles
• Lack a head and radula, with minimal cephalization
• Tentacles on the mantle
• Usually burrow in sandy or muddy soil
• Filter feeders, capturing food particles suspended in water
• Water is drawn in through an inlet siphon, carrying with it suspended particles.
• Particles are trapped in mucus and passed over gills.
• Filtered water is expelled through the outlet siphon.

Molluscs - Gastropods (Class Gastropoda)

• Examples include slugs, snails, abalones, whelks, conchs, limpets, and sea slugs
• Largest class of molluscs
• Many have a single, coiled shell (though not all)
• Well-developed head region

Annelids (Phylum Annelida)

• Examples include earthworms, marine worms, and leeches
• Segmented worms, mostly marine
• Well-developed coelom (fluid-filled body cavity) - acts as a hydrostatic skeleton, allowing independent movement of each body segment
• Can burrow in mud and crawl

Arthropods (Phylum Arthropoda)

• Possess rigid and jointed exoskeletons composed of chitin
• Must molt to grow
• Segmented bodies with paired appendages for various functions including feeding, reproduction, and locomotion.
• Include a well-developed central nervous system, often with brains and ventral nerve cords.
• Employ diverse respiratory systems, including gills, book lungs, and tracheae.
• Many undergo metamorphosis, with distinct larval and adult stages.

Arthropods - Crustaceans

• Examples include shrimps, lobsters, crayfish, crabs, barnacles, and krill
• Majority live in marine and aquatic environments
• Possess exoskeletons
• Many have compound eyes and five pairs of appendages

Arthropods - Centipedes

• Each segment has one pair of walking legs
• Prey on small crustaceans, insects, and worms

Arthropods - Millipedes

• Each four thoracic segments have one pair of legs
• Each abdominal segment has two pairs of legs
• Primarily herbivores

Arthropods - Insects

• Body with three parts: head, thorax, and abdomen
• Three pairs of legs on the thorax, some with one or two pairs of wings
• Head contains sensory organs and mouthparts
• Abdomen contains most internal organs
• Many undergo complete metamorphosis

Arthropods - Chelicerates

• Examples include spiders, sea spiders, scorpions, ticks, and mites, horseshoe crabs
• Terrestrial, aquatic, and marine environments

• 35,000 species of spiders

• 1,500 species of scorpions

• Have appendages attached to the cephalothorax
• First pair (chelicerae) for feeding and defense
• Second pair (pedipalps) for feeding or sensory functions
• Four pairs of walking legs

Echinoderms (Phylum Echinodermata)

• Consist of sea stars, sea urchins, sea cucumbers
• Bottom-dwelling marine animals, exhibiting radial symmetry
• Possess an endoskeleton composed of calcium-rich plates with spines
• Have a central nerve ring with branches

Water vascular system

• Used for locomotion, feeding, gas exchange, and sensory reception

Chordates (Phylum Chordata)

• Bilateral symmetry
• Deuterostome animals
• The first opening formed during embryonic development becomes the anus
• Subphylum Cephalochordata (non-vertebrates)
• Subphylum Urochordata (non-vertebrates)
• Subphylum Vertebrata
• Most chordates are vertebrates (possessing a vertebral column)

Vertebrates (1)

• Possess internal skeletons (bone or cartilage), and muscles attached allowing for greater freedom of movement and larger size compared to invertebrate animals
• Characteristics include notochord, a dorsal supporting rod below the nerve cord (replaced by vertebral column in vertebrates), a dorsal tubular nerve cord, and pharyngeal pouches (important for respiration in some vertebrate groups).

Vertebrates (2)

• Amphibians (Class Amphibia), typically having larvae that live in water. and adults that live on land with limbs, and smooth, nonscaly skin. Often using a mix of lungs and skin for respiration.
• Reptiles (Class Reptilia), generally have scales, a completely developed hard bony skeleton and well-developed lungs that allow them to live on land.
• Birds (Class Aves), are endothermic, warm blooded animals, with feathers, modified skeleton, efficient lungs, and an enhanced circulatory and respiratory systems allowing for flight
• Mammals (Class Mammalia) are endothermic, warm-blooded animals that often have hair or fur. They nourish their young with milk produced by mammary glands.

Seed Plants

• Adaptations to terrestrial environments, such as a waxy cuticle to prevent water loss
• Vascular tissues for transport of water and nutrients
• Seeds for protection and dispersal of embryos and nutritive material for the growing seedling
• Heterosporous producing both microspores (developing to pollen grains) and megaspores (developing to female gametophyte-embryo sac)

Flowers and Pollination

• Flowers often have colorful petals and produce scents to attract pollinators
• Wind pollination is common in some species, whereas others rely on insects, birds, or bats.
• Pollination, the transfer of pollen from anther to stigma, leads to fertilization and the development of seeds.

Biodiversity

• The variety of life
• Richness and complexity of a biological community
• Includes genetic, species, and ecological diversity
• Valuable for direct economic use (foods), genetic resources (medicine), and ecological stability.

Threats to Biodiversity

• Human activities (habitat destruction, pollution, overexploitation), invasive species, and climate change are major threats.

Conservation and Restoration

• Ecological restoration aims to return degraded ecosystems or habitats to a more similar state to their pre-degradation condition.
• Protection of biodiversity involves ecological restoration, rehabilitation, and creation of artificial ecosystems.

Marine Ecosystems

• Marine ecosystems are diverse and include a wide range of habitats and species
• Major threats to marine ecosystems include overfishing and coastal developments
• Case study of marine parks and marine reserves in Hong Kong provides information about conservation.
• Artificial reefs have been used to enhance habitats and biodiversity in areas with limited natural features.

Water and its importance

• Important to life on Earth, covering about 71% of the Earth's surface
• A crucial component of many life processes
• It plays a significant role in regulating Earth's temperature and climate
• It dissolves many important substances, and is vital for numerous biochemical processes essential for life.