Nekton

• The nekton can swim against an ocean current and include most fish, sharks, whales, seals, dolphins, squid, etc.

• We will discuss the characteristics and adaptations of whales and fishes only.

Whales

• Whales are marine mammals that breathe air, are warm-blooded, and feed milk to their young, just like humans

• There are two main groups of whales:– those with teeth– those with baleen

Toothed Whales

• These include dolphins, porpoises, killer whales, belugas, and sperm whales

• Sperm whales are the largest toothed whale. They can dive to great depths (1000m) and stay under for an hour. They feed mostly on squid.

Baleen Whales

• Include all the largest species of whales - blue, fin, sei, humpback, minke, right

• They have 300-500 plates of baleen that hang from each side of the upper jaw instead of teeth, which they use to sieve krill out of the water

• An average humpback will eat 1-1.5 tons of krill per day

Interesting Whale Facts

• Blue whales are the loudest animals on Earth! Their call reaches levels up to 188 dB. This whistle can be heard hundreds or perhaps even thousands of miles away. The blue whale is louder than a jet, which reaches only 140 decibels!

Interesting Whale Facts

• Orcas are the fastest whales, reaching speeds of up to 48 km/hr

• Humpback whales sing the most complex songs – only males sing

• Narwhals have the longest tooth – 7-10 feet long

Adaptations of Whales

• Streamlined bodies• Powerful tail flukes• Thick blubber layer to keep warm• Twice as many red blood cells as other land

mammals• During dives - heart rate slows to conserve

O2

• Water-tight seals on blowholes

Video: Mammals of the Sea

Fish

• Fish are cold-blooded animals and possess gills for breathing and fins for swimming

• They live near the surface to the ocean depths, in warm water and icy water

• There are two main groups of fish:– Cartilage fish (sharks, skates and rays)– Bony fish (tuna, cod, halibut, etc)

Cartilage Fish

• Cartilage fish lack bones and have a skeleton made out of cartilage (the stuff that is in your nose)

• Cartilage fish are negatively buoyant – will sink if they stop swimming

• Skates and rays have flattened bodies and wing-like fins

Sharks

• Most sharks have several rows of teeth, but some are planktonic filter feeders (whale shark, basking shark)

• Predatory sharks have a keen sense of smell and are able to detect vibrations in the water to locate prey

Sharks in Our WatersBasking

PorbeagleGreat White

Other Cartilage

Fish

                                                

Bony Fish

• Bony fish display the greatest diversity of all the vertebrates

• Possess air-filled swim bladders to aid in buoyancy

• 86 million tons of fish are taken each year for food

Bony Fish, cont’d

• Sight and hearing are well-developed to obtain prey and avoid predators

• Bony Fish also have a lateral line system which is a series of pores along the side of the fish. It is used to detect vibrations in the water

Some Unusual Bony Fish

                                   

Adaptations of Fish

• Hydrodynamic torpedo shaped bodies• Well-developed muscles for swimming• Fins specialized for the particular fish’s

mode of life• Countershading (dark on the dorsal

side; light on the ventral) – aids in camouflage from prey and predators

Label the Fish Parts

Types of Caudal Fins

Slow Fast

Video: Fish