Pannasastra University of Cambodia

Course: Marine Biology

Lecturer: Chea Leng

Topic: Challenges of Life in the Sea

Group 3

Thap Rachana

Khem Chhor Vida

Seng Bunthoeun

Seng Rithy

Soun Vattanak

CONTENT

I. Challenges of Life in the Sea

II. Salinity

– Diffusion and Osmosis

– Regulation of Salt and Water Balance

III. Temperature

IV. Surface-to-Volume Ratio

CHALLENGES OF LIFE IN THE SEA

SALINITY

• Salinity is the saltiness or dissolved salt content of a body of water.

• Many enzymes and other organic molecules are very sensitive to change in the concentrations of the ions that are common in seawater.

• Salinity in rivers, lakes, and the ocean is conceptually simple, but technically challenging to define and measure precisely. Conceptually the salinity is the quantity of dissolved salt content of the water.

Salinity Change of Ocean

DIFFUSION

Diffusion is a spontaneous

movement of particles from

an area of high concentration

to an area of low

concentration.

Goes from a high concentration gradient to a low

concentration gradient.

Does not need water for movement.

http://163.178.103.176/Fisiologia/gen_pracb_dinamica3.html

DIFFUSION

Diffusion mainly occurs ingaseous state or withingas molecules and liquidmolecules.

• Example: The molecules of 2 gases are inconstant motion and if the membraneseparating them is removed the gases willmix because of random velocities.

http://www.diffen.com/difference/Image:Diffusion.svg

OSMOSIS

• Osmosis is the spontaneous net movement of

water across a semipermeable membrane from a

region of low solute concentration to a solution

with a high solute concentration, down a solute

concentration gradient.

• Moves down concentration gradient.

• Needs water for movement.

OSMOSIS

• It occurs when the medium surrounding the cell has a higher water concentration than the cell.

• The cell gains water along with important molecules and particles for growth.

• It also occurs when water and particles move from one cell to another.

http://www.ias.ac.in/initiat/sci_ed/resources/chemistry/

physical.html

REGULATION OF SALT AND WATER BALANCE

Two major types of osmoregulation are osmoconformers and osmoregulators.

• Osmoconformers match their body osmolality to their environment actively or passively.

• Most marine invertebrates are osmoconformers, although their ionic composition may be different from that of seawater.

https://en.wikipedia.org/wiki/Osmoregulation#/media/File:Bachforelle_o

smoregulatoin_bw_en2.png

TEMPERATURE

Temperature refers to the measured amount of heatin a place or in the body.

Organisms are greatly affected by temperature.Metabolic reactions proceed faster at hightemperatures and slow down dramatically as it getscolder.

Poikilotherms

• Poikilotherms are most animals, including reptiles, fishes and amphibians, and include invertebrate species.

• They could not keep their body temperature constant, instead it is close to that of their surroundings, so when their body temperature is high.– Example: On a hot summer's day, they

can be very active, but when it is low, for example on a cold winter's night, they can produce energy only slowly.

Homoiotherms• Their living does not depend

on the temperature of their surrounding.

• Homeotherms can keep their body temperature almost constant. Warm-blooded animals are also often known as endotherms.

• All mammals usually have a body temperature of about 36oC and all birds usually have a body temperature of about 42oC.

SURFACE-TO-VOLUME RATIO

Adaptations to salinity and temperature are needed :

• Salt and heat can flow into and out of organism• Exchange nutrients• Waste products• Gases One thing that determines the S/V ratio is the size

of the organism• Organisms grow larger• Small organisms have a larger S/V ratio than big

ones• Small organisms ( single-celled ones)

THANK YOU