AT1 ORGANISMS

• Species A - Periwinkle

  • Broad tolerance for environmental conditions
  • Muscular foot adapted for clinging to various substrates
  • Ability to graze on algae provides food source across tide levels
  • Broad ecological niche to exploit diverse microhabitats
• Species B - Neptune's Necklace

  • Thrives in low to high tide zones
  • Tough, flexible fronds withstand wave action
  • Gelatinous texture and cylindrical shape retain moisture
  • Thickened cell walls prevent dehydration
• Periwinkle


  • Gastropod with broad tolerance for environmental conditions
  • Able to inhabit various tide levels
• Periwinkle


  • Possess muscular foot adapted for clinging to various substrates
  • Able to inhabit both exposed and submerged areas on the rock platform
• Periwinkle


  • Ability to graze on algae provides them with a food source available across different tide levels
• Periwinkle


  • Exhibit a broad ecological niche, enabling them to exploit diverse microhabitats within the low to high tide zones
• Periwinkle shell


  • Conical or spiral-shaped to help protect from predators and desiccation
• Periwinkles living in higher tidal zones

  Have thicker shells compared to those in lower tidal zones
• Periwinkle


  • Possess an operculum, a hard plate-like structure attached to the foot, which they use to seal the shell shut when withdrawn into the shell
• Periwinkle


  • Have a muscular foot that they use for movement and attachment to substrates to avoid being dislodged by waves or predators
• Periwinkle


  • Ability to adhere to rocky surfaces and withstand exposure to air and water fluctuations enables them to inhabit both low and high tide zones
• Periwinkles can inhabit both low and high tide zones without preference for a specific tide level
• Periwinkles can withstand exposure to air and water fluctuations
• Periwinkles can inhabit both exposed and submerged areas on the rock platform
• Periwinkle vertical migration


  1. Move up the rocky substrate to higher elevations during high tide to avoid being submerged by water and potentially drowned

  2. Increased activity during low tide when exposed to air and have access to more substrate for foraging
• The timing of reproductive behaviours such as mating and egg-laying in periwinkles is often synchronised with tidal cycles
• Periwinkle physiological adaptations


  • Desiccation resistance - Thickened, impermeable cuticle to reduce water loss
  • Osmoregulation - Ability to regulate salt concentrations despite fluctuating salinity
  • Temperature tolerance - Behavioural and physiological mechanisms to cope with temperature fluctuations
  • Metabolic rate adjustments - Ability to modulate metabolic activity to match environmental conditions, conserving energy during low tide
• Periwinkle symbiosis


  • Epibionts - Periwinkles host algae, barnacles, or small invertebrates on their shells, providing camouflage and protection
  • Mutualistic algae - Some periwinkles harbour photosynthetic algae within their shells, which produce oxygen, benefiting the periwinkle, particularly during low tide
  • Commensal relationships - Periwinkles may house small amphipods or isopods in their shells without harm, providing shelter, and protection
  • Parasitic relationships - Periwinkles can serve as hosts to parasites such as trematode flatworms or parasitic copepods, impacting their health and behaviour
• Periwinkle predation


  Predation risk often varies with tide levels
• Periwinkles may seek refuge under rocks or in crevices during low tide to avoid predation, while during high tide, they may rely on their shell's camouflage and defensive mechanisms
• Neptune's Necklace


  • Thrives in low to high tide zones where it is submerged during high tide and exposed during low tide, able to retain moisture
  • Tough, flexible fronds allow it to withstand wave action during low tide
  • Gelatinous texture and cylindrical shape help withstand lack of moisture during low tide periods
  • Cells have thickened walls acting as barriers to water loss, preventing dehydration
• Neptune's Necklace structure


  • Branches made up of strings of hollow, water-filled, round or oval-shaped beads joined together by a short stalk
  • Each bead is covered in many pores
  • Dark brown colour with some green, coated with a waxy layer to prevent water loss and dehydration
• Neptune's Necklace


  • Modified leaves with small bladders store water to prevent dehydration
  • Bladders also contain air, allowing the seaweed to float above other plants and compete for light
  • Often occurs in vast colonies forming a thick covering over most of the rock surface
  • Strong attachments to rocks prevent the plant from being washed away by waves
• Neptune's Necklace physiological adaptations

  • Slime coat helps prevent drying out when exposed to air or wind
  • Capable of making its own food through photosynthesis
  • Has mechanisms for regulating internal salt concentration, allowing survival in both saltwater and freshwater environments
  • Reproduces both sexually and asexually
• Neptune's Necklace symbiosis


  • May engage in mutualistic relationships with certain species of bacteria or fungi, assisting in nutrient uptake, nitrogen fixation, or defence against pathogens
• Neptune's Necklace as a producer


  Eaten by herbivorous organisms like sea urchins, snails, and small fish species
• Neptune's Necklace


  Small species are consumed by squids, which in turn are consumed by sharks
• Neptune's Necklace environmental requirements

  • Thrives in temperate waters with relatively stable temperatures
  • Extreme temperatures can stress the algae
  • Requires a balance of saltwater to survive
  • Prefers areas with moderate water movement to avoid dislodgement or damage
• Neptune's Necklace energy source

  • Relies on sunlight for energy through photosynthesis
  • Adequate light penetration is essential for growth and productivity
• Neptune's Necklace preferred pH


  • Thrives in coastal marine environments with a pH typically ranging from about 7.5 to 8.5, preferring alkaline conditions