Animals of the Pelagic Animals of the Pelagic

Animals of the Pelagic

Animals of the Pelagic I. Animals utilize many strategies to float near the surface (euphotic zone) or maintain a specific depth within the oceans. Shark Riders

Animals of the Pelagic A. Gas containers – some have pockets of low density gas that make them bouyant. - A nautilus is a prime example of a cephalapod with a gas chambered shell.

Animals of the Pelagic B. Floating forms – soft gelatinous tissue with few hard tissue. 1. Coelenterate – soft body 95% water a. cnideria (jellyfish) 2. Tunicates – Barrel shaped, move via jet propulsion.

Animals of the Pelagic 3. Ctenophores “ten-off-ora” – 8 rows of cilia for movement. -eg. Comb jellies

Animals of the Pelagic 4. Chaetognaths– “key-toe-nath” aka Arrow worms- Transparent arrow-worms (a significant proportion of plankton.

Animals of the Pelagic C. Swimming forms. Larger animals utilize locomotion for buoyancy. 1. Many like squid use a siphon for jet propulsion.

Animals of the Pelagic 2. Others utilize fins a. Caudal for locomotion (tail) b. Vertical for stability (eg. Dorsal and anal fin) c. Lateral for manuverability (pectoral and pelvic). **Great White Bull Shark Dissection.

Animals of the Pelagic II. Adaptations for seeking prey A. Mobility – 2 basic stratagies 1. Lungers – sit and wait, then short burst to catch prey. 2. Cruisers – Constantly in motion, actively stalking prey.

Animals of the Pelagic - Red vs. white muscle- red muscle fiber is narrower in diameter and contains myoglobin. - Cruisers have higher percentage of red muscle tissue than lungers.

Animals of the Pelagic B. Speed – Speed is directly related to it’s body length. - the longer the fish, the faster it is.

Animals of the Pelagic C. Body temp – Warm blood is needed to maximize power output of muscles.

Animals of the Pelagic III. Marine Mammals – include herbivores and carnivores.

Animals of the Pelagic A. Mammals spending much of their time in the water but breed on land. 1. Sirenia (sea cows)– dugongs and manatees 2. Pinnipeds – Sea Lions, seals and walruses

Animals of the Pelagic B. Mammals spending all of their time in the water 1. Cetaceans – Whales, porpoises and dolphins.

Animals of the Pelagic C. Modifications for deep diving (mammals). 1. Breathing adaptations: They are better at absorbing O 2 from the air. 2. Gas volume changes with pressure. -Surface pressure is 1 atm (atmosphere) - Pressure increases 1 atm per 10 m.

Animals of the Pelagic D. Cetaceans (whales, dolphins, porpoises) 1. Toothed whales – Sperm whales, Killer whales, dolphins and porpoises. -predatory whales

Animals of the Pelagic 2. Baleen whales – Blue, Humpback, Rorqual, Grey and Right Whales. -have baleen – teeth modified into a filter for plankton.

Animals of the Pelagic 3. All whales are highly streamlined for fast locomotion – creates laminar (streamlined) flow near their bodies.

Animals of the Pelagic 4. They use echolocation to find prey, communicate and navigate.

Animals of the Pelagic IV. Group behavior. A. Schooling – well-defined social organizations of fish, squid and crustaceeans. -range from a few large predators to thousands of small filter feeders. - Moves at same speed in same direction. -Advantages in mate location and protection from predation.

Animals of the Pelagic B. Migration – 1. Many follow the same routes every year (gray whale) 2. Some are Catadromous – Example eels (live in fresh water and return to ocean to spawn) 3. Some are Anadromous – Example salmon (live in ocean and travel to fresh water to spawn).

Animals of the Pelagic C. Reproduction- some strategies 1. Oviparous reproduction – Reproduce by laying eggs (usually high in numbers).

Animals of the Pelagic 2. Ovoviviparious – eggs develop within an organism however, process is similar to Oviparous reproduction. -Example seahorse – female deposits egg in pouch of male where it develops until hatching.

Animals of the Pelagic 3. Viviparous reproduction – give birth to live young. -Much reduced in numbers, however, offspring much more developed.