Estuaries: the Ocean’s Nurseries

Ask anyone and they would tell you that water is one of the most important resources for everybody. So why does nature need water? Fishes need water to swim in and lay eggs, plants need water to grow, and some organisms live solely in water and depend on the moisture to survive. Why do we need water? Water is important to help us live, regulate our body temperatures, and grow sex video.

Often viewed as muddy, smelly, mosquito-filled swamps, estuaries and their associated salt marshes and tidal flats are among the most productive habitats in the world. They are mixing zones, where freshwater, delivered by rivers and streams, flows into water from the sea. Animals and plants in this habitat must be able to tolerate wide ranges of salinity and temperature, as well as fluctuating water levels. Nutrient-rich estuaries protect and nurture a variety of shrimp, oysters, crabs, and fishes. Over 490 species of birds live in or migrate through the Coastal Bend of Texas, and many use the estuaries to feed, rest, and find shelter.

Seagrasses are plants that root, pollinate, and spend their entire lives submerged in shallow waters. Special adaptations allow for their survival in the fluctuating conditions of coastal bays and estuaries. The estuaries in the Coastal Bend of Texas contain 40% of Texas’ total seagrass acreage. Seagrasses provide oxygen, nutrients, anchorage, food, habitat, cover, and places for attachment.


Bay System Seagrass
Meadow Area* Area of
Bay Bottom* Percent Seagrass
Galveston Bay _____ 391 _____143,153 _____ _____
Matagorda Bay _____ 1,096 _____ 101,368 _____ _____
San Antonio Bay _____ 2,743 _____ 54,335 _____ _____
Aransas Bay _____ 2,455 _____ 47,267 _____ _____
Corpus Christi Bay _____ 5,249 _____ 43,550 _____ _____
Upper Laguna Madre _____ 24,900 _____ 33,100 _____ _____
Lower Laguna Madre _____ 48,200 _____ 68,400 _____ _____

* All measurements are in hectares.


The Texas bay systems above are listed in order from north to south. Use the measurements provided to calculate the percent seagrass coverage in each bay.
Rank the measurements in each category. Number one through seven from largest to smallest. Record the rankings in the blanks to the left of each measurement, including percent seagrass coverage.
Examine the rankings. Do you see any relationships between the measurements provided and percent seagrass coverage? How about location north and south? If, so, explain.

Seahorses are among the most unusual-looking animals in the world. Unlike most fishes, they lack the caudal, or tail, fin. Most fish species use the caudal fin to propel themselves through the water. Lacking that, the seahorse uses its dorsal and pectoral fins to propel itself.
The seahorse has a unique tail in that it is prehensile or grasping. Just as monkeys are able to use their prehensile tails to grasp and swing from trees, seahorses are able to use their tails to grasp seagrasses, algae, and other stationary objects.

Humans have thumbs which similarly allow them to grasp objects. This is one adaptation that has contributed to our ability to use tools and manipulate objects easily.


Gather a collection of at least ten tools and objects (screwdriver, hammer, coins, etc.).
Divide a sheet of paper into three long columns. List the tools and objects down the page in the first column. Label the second column “with thumb” and the third column “without thumb.”
Manipulate each tool and lift each object. Rate the effort required to perform each task on a scale of one to ten, with ten being very easy and one being very difficult. Write your rating in the second column.
Fold your thumb across your palm. Using the masking tape, tape your thumb in place.
Re-do each of the tasks that you performed earlier. Rate the difficulty of each task on the one to ten scale.
Compare your ratings with and without the use of your thumb. List other tasks that would be affected by the presence or absence of thumbs