When mountain lions consume large prey, they often leave large pieces of their prey behind. The carcass that is left becomes a food source for other organisms. A scientist reported a count of 24,000 beetles in an area where mountain lions had left partially eaten carcasses. Wolves, bears, and other animals also take advantage of the remains of the prey.

Ladybugs that eat plant pests are currently raised and sold commercially to gardeners. It was assumed that all of the imported ladybugs would remain within the garden area and consume only the harmful insect pests. It is now known that the ladybugs can travel widely, with one study showing that within a few days, 99% had left the area where they were originally released.

Many species of warblers, including the Blackburnian warbler shown below, migrate from Central and South America to New York State, where they breed each summer. Warblers primarily prey on insects and nest in hemlock trees. An invasive insect, the wooly adelgid, is killing hemlock trees across the entire state. If this continues, fewer warblers will be able to find suitable nesting sites.

Mammals, including humans, dolphins, and cows, produce milk for their young. Surprisingly, researchers have discovered that certain spiders also produce a milk-like fluid for their young. The spider leaves droplets of her “milk” around the nest for the babies after they hatch from their eggs. After one week, the babies will feed on the “milk” directly from her body for at least 20 days.

The New Mexico whiptail is a female-only species of lizard that exhibits an unusual form of asexual reproduction. Researchers discovered that these lizards produce eggs that have a full set of chromosomes and have the genetic diversity of sexually reproducing lizards.

Drinking Water Is Just The Beginning! The amount of water taken in must be in balance with the amount lost. The urinary system is involved in maintaining the salt and water balances within the body.

Each kidney is composed of about a million waste-filtering structures known as nephrons. Water is reabsorbed through some parts of the nephron, such as the tubule. The model below shows the structure of a nephron in two organisms.

Another function of the kidney is to aid in regulating the number of red blood cells. The kidneys produce a protein known as Erythropoietin (EPO) that stimulates the increased production of red blood cells. The graph below shows the results of a study. Participants were exposed to different conditions prior to time zero, then EPO levels were measured over a 4.5-hour time period.

In addition to their other functions, red blood cells (RBCs) have the capacity to carry water. The surface of the cell contains structures called aquaporins, which transport water across cell membranes. Due to their unique cell structure, RBCs are able to expand up to 74% or shrink up to 40% compared to the original cell size.

RBCs typically have a biconcave disk shape. A scientific study examined the effect of changing the RBC shape and membrane flexibility on its ability to transfer oxygen. For this study, when the RBC membrane was less flexible, the oxygen transfer capacity decreased by 18%. When the RBC was more flexible, the oxygen carrying capacity increased by 21%. When RBCs take on water their membrane initially becomes more flexible.

Lions in East Africa are night hunters. They are most successful during the darker phases of the moon, when they are less visible. Prey animals, such as the wildebeest shown below, are also influenced by the moon cycles and amount of darkness. During the dark phases of the moon, they are less active.

Material cycles are necessary to recycle substances needed and used by organisms in their habitat. The atmosphere is composed of about 80% nitrogen gas (N2) that cannot be used by most organisms in that form. It is through the action of many different types of bacteria that the nitrogen gas can be made available to other organisms. The diagram below represents a model of the nitrogen cycle.

Male Pacific field crickets make a loud song that travels a long distance to attract females. They use their wings to create the sound. On the island of Kauai, the loud calls not only attract mates, but also a specific fly species. The fly deposits larvae on the cricket. As the fly larvae mature, they eat the cricket from the inside out.

One summer, observers on Kauai noticed that the crickets were unusually quiet. They also noticed that the wings of these quiet crickets were shaped differently. The scientists hypothesized that the wing mutation helped crickets escape the fly. They collected the following data while testing their hypothesis:

For 20 days, two groups of plants, all with stems of the same length, were grown at two different temperatures. These plants normally grow at a temperature of 25°C. All other environmental conditions were the same. The stem lengths of the plants were measured every five days, averaged, and the data recorded in the table below.

Sea Otters at Risk

A single-celled parasite is responsible for the death of a large number of sea otters. Scientists have traced the origin of the parasite to multiple sources, including domestic cat feces. Rain washes some litter box wastes, which contain cat feces, into the ocean kelp forests where sea otters live.

Lead in the Environment

Soil contaminated with lead is a source of lead exposure in people and is a worldwide health concern. Scientists examined the relationship between exposure to lead in the topsoil and the occurrence of learning difficulties in children. Soil clings to fingers, toys, and other objects. When young children are exposed to lead, they can experience difficulty with remembering, concentrating, and learning.

Lead was used as a gasoline additive until 1996, when it was banned. Emissions from cars and trucks resulted in a buildup of lead in the soil along the side of the road. In a recent study, scientists measured the concentration of lead along sections of the interstate highway system. They then compared the levels of lead in the soil along the side of the road with the number of children in the area experiencing cognitive difficulties. The scientists discovered that where the level of lead in the soil is high, the number of children with learning difficulties is also high.

Beavers have been migrating north and impacting Arctic ecosystems. By building dams on streams, beavers are creating new bodies of water where there were none. These new bodies of water contribute to the thawing of the frozen permafrost soil, which is a huge natural reservoir of stored greenhouse gases. In a study of beaver dams located on Alaska’s Baldwin Peninsula, there was a total of 94 dams in 2010, and by 2019 there was a total of 409 dams.

Why Do Marimo Balls Float and Sink?

Marimo are fuzzy, round balls of a rare algae that is native to some cold, freshwater lakes. They have been observed to float after dawn and sink after dusk. A group of scientists conducted experiments to determine the cause of this floating and sinking action.

In one experiment, a marimo ball was placed in a graduated cylinder with 500 mL of water and exposed to light for four minutes. After four minutes, the light was turned off and the marimo was kept in the dark for another four minutes. The position of the marimo was measured each minute by recording the location of the marimo in the graduated cylinder with respect to the mL lines.

The experimental setup and data table are shown below. The data table gives the position of the top of the marimo in the cylinder during the eight-minute interval.

Adirondack Logging Results

A forested area in the Adirondacks was heavily logged in the early 1900s. The logging ended in 1915, leaving empty fields of grasses and some shrubs. Over the next 80 years, until 1995, the abundance of different plant species was recorded periodically to show the changes that occurred in the area. A graph representing these changes is shown below.

Why Honey Badgers Don’t Care

The honey badger, found in parts of India, Africa, and the Middle East, has been identified as “the world’s most fearless creature” by the Guinness Book of World Records. Although they are primarily carnivorous, honey badgers consume a wide variety of food: rodents, insects, bee larvae, birds, and fruit. Venomous snakes, including cobras and puff adders, are also favorite items on their menu.

As much as 25% of a honey badger’s diet consists of venomous snakes with fangs. The adaptation to withstand snake venom has enabled them to be one of the only predators to feast on this source of meat. They hunt fairly slow-moving prey with fangs rather than fast prey with claws and teeth.

Snake venom contains more than 100 proteins that could potentially poison a honey badger—meaning that honey badgers need multiple defenses. Scientists have focused their research on a nasty class of molecules in cobra venom called alpha-neurotoxins, that paralyze the muscles associated with breathing. These neurotoxins block a specific receptor and therefore prevent muscle cells from receiving signals from the nervous system.

Presently, most antivenoms used to treat snake bites are made of proteins produced by the immune systems of horses and sheep exposed to specific snake venoms. These proteins attack the venom directly in people bitten by a venomous snake.

Three Billion North American Birds Have Vanished Since 1970

Recent surveys of 529 bird species revealed that since 1970 the North American continent lost 3 billion birds, 29% of the total. Birds are excellent indicators of environmental health and are vital to ecosystems. Common bird species control insects, pollinate flowers, spread seeds, and help regenerate forests. As a result, when these birds disappear, their former habitats are not the same.

Many factors influence the bird populations. Loss of habitat to urban sprawl, converting grasslands into farmlands, and the use of pesticides to reduce insect populations have been particularly hard on some bird species. Changes to natural habitats can reduce nesting sites and limit flight paths for migratory birds. House cats that are allowed outside and feral cats contribute significantly to the loss of birds.

However, some birds have increased due to changes in human activities. Studies found that raptors (predators) such as bald eagles have rebounded after the pesticide DDT was banned. Waterfowl such as ducks and geese have also increased due to conservation programs.

The bobolink is a small blackbird whose population has undergone a decline of 75% in some regions. These birds nest in fields of tall grass during the summer across the northern United States and migrate long distances to winter in southern South America.

New research comparing the anatomy and behavior of dogs and wolves found that dogs have small facial muscles around their eyes which allow them to raise their inner eyebrow. This makes their eyes appear larger and more infant-like. Wolves do not have these muscles.

Scientists hypothesize that dogs expressing this “puppy-dog eye” trait unconsciously stimulate a desire in humans to take care of them. Examine the evolutionary tree below of modern dogs and their relatives.

Breaking Down Plastics Researchers collected soil contaminated with specific plastics outside a plastic bottle recycling facility. They discovered a type of bacterium in the soil that was able to depolymerize (break down) and use these plastics as a source of nutrition. A bacterial enzyme that could digest large molecules of plastic into their building blocks was isolated. Those building blocks can be used to produce new plastic products. Scientists have been working to improve the efficiency of this enzyme by altering the specific molecules the bacteria need to code for the synthesis of the enzyme. Using this method, many variations of the enzyme were produced by the altered bacteria, and these variants were tested.

The graphs below show a comparison of the activity of the original enzyme and two variants produced by the scientists.

Arizona Desert Food Web

Desert food webs are complex and often contain more food chains than a grassland or forest food web. This is important to the stability of the desert ecosystem. Relationships between organisms can be described as positive, negative, or neutral.

Positive relationship: Both species benefit.

Negative relationship: Either species would benefit if the other species were no longer present. T

Neutral relationship: the species have no effect on each other.

One group of students drew energy pyramid A to model where the energy is located in the Arizona desert food web. Another group of students drew energy pyramid B for their model.

In 1980 the red wolf was declared extinct in the wild. Only one small captive population survives in North Carolina. Recently a group of canines resembling coyotes but with red fur were discovered on an island near Texas. They are clearly a kind of coyote, but could possibly contain some red wolf genetic material.

A cat owner was devastated by the death of his beloved cat, Garlic. He contacted a cloning company that was able to produce Garlic 2.0 using DNA from preserved cells of the original cat. However, the client was disappointed to see that while Garlic 2.0 was very similar to his original pet, there were slight differences in the cloned cat’s appearance.

The embryo that became Garlic 2.0 was implanted into another cat, a surrogate mother shown in the photo below.

Lemurs of Madagascar

Lemurs are primates found only on the island of Madagascar, which is located about 250 miles off the coast of Africa. The ancestral species of lemurs arrived 40-50 million years ago (mya), long after Madagascar became an island. This concept is illustrated in the diagram below.