Skip to main content

Differences in Terrestrial and Aquatic Plants

Even though plants that live in water look dramatically different from terrestrial plants, the two groups have a lot in common. Both types of plants capture the Sun’s energy and use it to make food from raw materials. In each case, the raw materials required include carbon dioxide, water, and minerals. The differences in these two types of plants are adaptations to their specific environments.

Land plants are highly specialized for their lifestyles. They get their nutrients from two sources: soil and air. It is the job of roots to absorb water and minerals from the soil, as well as hold the plant in place. Essential materials are transported to cells in leaves by a system of tubes called vascular tissue. Leaves are in charge of taking in carbon dioxide gas from the atmosphere for photosynthesis. Once photosynthesis is complete, a second set of vascular tissue carries the food made by the leaves to the rest of the plant. Land plants are also equipped with woody stems and branches that hold them upright so that they can receive plenty of light.

Marine plants, called macroalgae or seaweeds, get their nutrients, water, and dissolved gases from seawater. Since water surrounds the entire marine plant, these dissolved nutrients simply diffuse into each cell. For this reason, marine plants do not have vascular tissue to accommodate photosynthesis or to carry its products
to each cell. In addition, marine plants do not need support structures because they are held up by the buoyant force of the water. Since water in the ocean is always moving, the bodies of marine plants are flexible, permitting them to go with that movement. Some marine plants secrete mucus to make their surfaces slick, further reducing their drag or resistance to water movement. Mucus also helps keep animals from eating them.

macroalgae or seaweeds
macroalgae or seaweeds

A plant that grows on land is described with terms such as leaf, stem, and root. Seaweeds are made up of different components, which are shown in Figure below. The parts of seaweed that look like leaves are termed blades, or fronds. Some are equipped with small, gas-filled sacs, or bladders, that help keep them afloat and close to the sunlight. The gases in these bladders are usually nitrogen, argon, and oxygen. The stemlike structures of macroalgae are referred to as stipes. A root-shaped mass, the holdfast, anchors seaweeds but does not absorb nutrients like true roots do. Together, the blades, stipes, and holdfast make up the body, or thallus, of the macroalgae. Thalli take on many different forms, including tall and branched or thin and flat.

The body, or thallus, of a macroalga is made up of leaflike blades, stemlike stipes, and rootlike holdfasts. Gas bladders on the stipes and blades help hold the plant near the top of the water column.
The body, or thallus, of a macroalga is made
up of leaflike blades, stemlike stipes, and rootlike
holdfasts. Gas bladders on the stipes and blades help
hold the plant near the top of the water column.

Popular posts from this blog

Advantages and Disadvantages of an Exoskeleton

More than 80 percent of the animal species are equipped with a hard, outer covering called an exoskeleton. The functions of exoskeletons are similar to those of other types of skeletal systems. Like the internal skeletons (endoskeletons) of amphibians, reptiles, birds, and mammals, exoskeletons support the tissues and give shape to the bodies of invertebrates. Exoskeletons offer some other advantages. Serving as a suit of armor, they are excellent protection against predators. Also, because they completely cover an animal’s tissues, exoskeletons prevent them from drying out. In addition, exoskeletons serve as points of attachment for muscles, providing animals with more leverage and mechanical advantage than an endoskeleton can offer. That is why a tiny shrimp can cut a fish in half with its claw or lift an object 50 times heavier than its own body.
Despite all their good points, exoskeletons have some drawbacks. They are heavy, so the only animals that have been successful with them …

Mollusks: Gastropods, Bivalves, and Cephalopods

The mollusks are a large group of arthropods that have a variety of outward appearances and include animals such as clams, octopuses, and snails. Because of their tremendous range of structures and styles, mollusks are divided into three groups: gastropods, bivalves, and cephalopods. Unlike their plainer terrestrial relatives, marine species of mollusks have extravagant forms that tend toward elaborately shaped shells and bright colors.
Even though the group is diverse, members share some common traits. The group’s name, mollusk, literally means “soft bodied” and describes one of their primary characteristics. In addition to soft bodies, mollusks are also characterized by a foot that is used for locomotion. Internally, mollusk organs are covered with a thin tissue called the mantle. In some species the mantle secretes the shell and one or more defensive chemicals, such as ink, mucus, or acid.
A mollusk feeds with a file-like rod of muscle called the radula. This tongue-like organ is c…