Habitats, food webs and adaptations

Riley and Steve Hathaway want to change the way young people think and act towards the ocean. Their vision is to “Inspire kids to enjoy and care for the world’s oceans”.

Science ideas and concepts in Young Ocean Explorers

In between the smiles, light-hearted banter and stunning underwater shots, Riley introduces a number of important science concepts:

• A habitat is the natural home or environment of a living thing.
• In a food web, energy and nutrients are passed from one living thing to another.
• Adaptation is an evolutionary process in which an organism becomes well suited to living in a particular habitat.

Resources on the Science Learning Hub provide an in-depth means to further explore these concepts.

Marine habitats

Riley explores several marine habitats. In Harbours (episode 2), she discovers a busy underwater city that acts as a crèche for young fish, providing them with food and protection.

While exploring the kelp forests in episode 8, Riley finds snails, shrimps, crabs and sponges living among the seaweed.

New Zealand’s marine environment is incredibly diverse and is made up of a large number of habitats. Different habitats have different characteristics due to wave action, light, temperature substrate (sandy or muddy) and other factors. For example, Sandager’s wrasse fish (episode 6) need a habitat with a sandy floor, as this is where they sleep. Sea turtles (episode 9) visit New Zealand but don’t live here because the water is too cold.

Marine food web

As Riley learns about rays (episode 1), crayfish (episode 3), orcas (episode 4) and sharks (episode 10), she mentions the food these creatures like to eat – and what eats them as well. In any food web, energy and nutrients are passed from one living thing to another. Food webs vary according to habitat, but all food webs have some things in common.

Primary producers make up the base of a food web. Phytoplankton, seaweeds like kelp (episode 8) and seagrasses make their own food by converting energy from the Sun through photosynthesis. Consumers cannot make their own food so they need to get food from other sources. For example, Riley tells us that rays eat shellfish, crabs and fish, but in turn, rays are eaten by sharks and orcas. Another important but often overlooked part of the food web is the decomposers. Bacteria and other organisms break down dead plants and animals, releasing the nutrients back into the ecosystem.

Adaptations of marine creatures

Riley explains some of the unusual characteristics of creatures found in New Zealand’s seas. These characteristics enable the creatures to live in a particular environment and are often referred to as adaptations. Adaptations are generally grouped into three main categories: structural, physiological and behavioural.

Structural adaptations are the physical features of the organisms. For example, crayfish (episode 3) have spiky exoskeletons for protection because everyone wants to eat them! Kelp (episode 8) has honeycomb cells filled with air to help it bounce back from ocean waves. Kelp’s slimy coating protects it when the tide is out. Rays (episode 1), dolphins (episode 7) and sharks (episode 10) all have specialised teeth and eyesight to help them hunt or survive being hunted.

Physiological adaptations enable an organism to regulate how its body functions. For example, Sandager’s wrasse fish (episode 6) are all born female, but if a group’s male dies, the ‘bossiest’ female in the group becomes a male fish within 2 weeks.

Behavioural adaptations are learned or inherited behaviours that help an organism survive. For example, adult orcas (episode 4) teach their young how to hunt in groups and communicate with others in their pod to surround their prey.