Sponges are similar to other animals in that they are multicellular, heterotrophic, lack cell walls and produce sperm cells. Unlike other animals, they lack true tissues and organs, and have no body symmetry.
The shapes of their bodies are adapted for maximal efficiency of water
flow through the central cavity, where it deposits nutrients, and leaves
through a hole called the osculum. Many sponges have internal skeletons of spongin and/or spicules of calcium carbonate or silicon dioxide. All sponges are sessile
aquatic animals. Although there are freshwater species, the great
majority are marine (salt water) species, ranging from tidal zones to
depths exceeding 8,800 m (5.5 mi).
Answer:
D
Explanation:
Vegetation on soil protects the soil from erosion because its roots and root hairs help bind the soil particles together. This occurs mechanically by binding soil into crumbs and also chemically by providing organic matter that binds the soil particle into humus that holds moisture. The soil becomes heavy to be carried off by wind erosion. Trees also break the down flow of water hence reducing the capacity of runoff to carry soil sediments.
A. All distant galaxies are moving away from us.
Acceleration is a little more complicated. It is defined as the rate of change of the object's velocity over its change in time. ... Or, if the acceleration is negative, it's called deceleration and describes something slowing down. For something to speed up or slow down, it has to have a certain change in velocity
Rigid skeletons are formed from materials including chitin (in arthropods), calcium compounds such as calcium carbonate (in stony corals and mollusks) and silicate (for diatoms and radiolarians).
