5
from severe storms and also to hide from
sharks. The otters feed on sea urchins
and other marine invertebrates (creatures
without backbones, such as sea stars,
crabs, and jellyfish) that graze on giant
kelp. Invertebrates eat massive quantities
of kelp and can destroy an entire forest
if left to multiply unchecked. By feeding
on sea urchins, sea otters help keep the
population of these creatures under con-
trol. As a result, the kelp forest continues to grow and thrive,
providing a habitat for the rich diversity of wildlife species that
depend on it for survival.
Habitat Loss
No matter where habitats are located, the greatest threat to them
is human actions: pollution, the leveling of forests for farmland,
cutting up land for development and road building, filling in wet-
lands, and global warming. These actions have damaged or de-
stroyed many of earth’s wildlife habitats, which endangers wildlife
and puts species at risk for extinction. “Every day there are fewer
places left that wildlife can call home,”
1
says the National Wildlife
Federation.
Wildlife scientists categorize habitat loss as one of three major
types: destruction, fragmentation, and degradation. Some ways
habitats are destroyed include harvesting fossil fuels such as coal,
clear-cutting forests, and filling in wetlands. Habitat fragmentation
occurs when habitats are cut up into fragments for road building or
residential or industrial development. Marine wildlife can also lose
habitats through fragmentation, such as when dams are built or
water is diverted in other ways. Equally hazardous is habitat deg-
radation, which is most commonly caused by pollution from un-
treated sewage, mining waste, fertilizers, and pesticides, among
other substances.
According to the World Wildlife Fund (WWF)
Living Planet
Report 2016
, earth’s population of wild vertebrates (mammals,
birds, reptiles, amphibians, and fish) declined 58 percent from
WORDS IN
CONTEXT
invertebrates
Wildlife species
(marine and land)
without backbones.
