Research
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Introduction 
When most people think of New York City, they usually think about the incredible diversity of the people who live in and visit the city. One thing that usually doesn’t cross their minds is the teeming wildlife that lurks beneath the surface of the city. The wildlife of New York is just as diverse, if not more, than its citizens. Specifically, it was the invertebrates that live out of sight that piqued our interests. Invertebrates are technically defined as animals without backbones (A.K.A the vertebral column). These are not the fish, turtles, horses, birds, squirrels, dogs, cats, or mice that we are familiar with. In fact, the animals we usually think of tend to have an exaggerated importance, mainly due to the fact that they are quite large and make themselves known. Invertebrates, in contrast are the animals that we are least familiar with: ants, spiders, flies, butterflies, cockroaches, and bed bugs (All examples of Arthropods). They are small and reclusive. Surprisingly, they make up 97% of the documented species on planet earth, and they play a pivotal role in the biosphere.
Vertebrates and Invertebrates
The differences between vertebrates and invertebrates lie deeper than the fact that one group has a backbone and the other does not. Vertebrates evolved relatively recently in the evolution of species, while invertebrates have been around for much longer in our history. Vertebrates have a shared body plan (a blueprint for the organism’s shape and structure), while invertebrates do not have a shared body plan and instead, they feature over 30 body plans, all of which are fundamentally different from each other. The examples given above are just a small subset of the diversity to be found among the invertebrates. The focus in this paper will be on the invertebrates most likely to be found in the parks and natural spaces of New York City. These will be the arthropods (examples given above) and the annelids (such as earthworms).
Biological Processes
All organisms share the need to do things that will keep them alive. The same way that people must nourish themselves with food and water on a periodic basis, so must all animals. An animal does not cease the progress of its internal machinery until the moment it is dead. The following are just some of the things an animal must do to survive:
Locomotion – Animals must be able to move or at least have moving parts such that they can search for food and escape from predators. The many various forms of locomotion found among animals stem from the body plan of the animal and the medium through which it moves (by land, by sea, or by air). Some animals happen to be sessile (attached to a surface) at one point or another in their life cycle; these animals have moving parts that they can use for feeding.
Feeding – The vital task of eating and digesting food is coordinated by sensory receptors that feed an animal information about the environment and the physical mechanisms required to move or to eat. As it is consumed, food is not immediately ideal for incorporation into the cells of the body and as a usable source of energy. It must first be broken down by the action of digestive fluids secreted into the digestive system. Almost all animals have internal cavities to carry out digestion. Some animals, like the earthworm, have a simple tube running from the mouth to the anus, while others are more complex.
Citizen Science
Scientists are not the only ones who can contribute to the growing amount of scientific knowledge. Amateur scientists and enthusiasts, also known as citizen scientists, can also take part in the data collecting stage of a scientific experiment. Several key questions arise regarding the accuracy of measurements obtained by citizen scientists. How reliable is the data? In some fields, data collection may not be so difficult that the volunteers aren’t able to do it. With the proper training, anyone can contribute to scientific research. Because enthusiasts and hobbyists do not have the same knowledge and experience as researchers, it’s best to limit what they are asked to do. By having less to do, but being more precise about it, citizen scientists can be of real use to science.
Citizen Science was used to conduct research into the invertebrates of New York City. Members of our team met up on weekends and visited different parks in the city to look for invertebrates such as spiders, centipedes, pillbugs, ants, ladybugs, slugs, and earthworms. The expeditions were fairly successful and a good number of animals were found in each visit. It is likely that more would have been found during the warmer months as compared with those found in late Fall. Our group uploaded its findings to the online community site iNaturalist through an iPhone app. The purpose of this is two-fold: it documents our groups’ travels and it also allows other members of the online community to identify unknown specimens. The specific project to which uploads were sent is named New York is Wild!.
An additional component to citizen science is the educational aspect. Volunteers learn more about science as they go about collecting data. The important ideas surrounding science education may be found in Surrounded by Science and are characterized by 6 learning strands.
The first learning strand is “Sparking Interest and Excitement”. It encompasses the motivational aspect of science learning. Citizen Science accomplishes this strand directly by putting the learner in direct contact with the natural world. It turns out that the emotions associated with interest are the same ones that help people learn, remember, and retain information. This strand is one of the strengths of informal science learning.
The second strand is “Understanding Scientific Content and Knowledge”. This is best accomplished by accompanying the science learner with a science educator who has prior knowledge in the field. Sophomores of the Macaulay Honors College took part in the 2013 BioBlitz in Central Park, where they were tasked with identifying different organisms. An expert accompanied each team. The expert not only assisted with making correct identifications, but also functioned as a facilitator of knowledge for the students by introducing new concepts and ideas as they came up during the event. This strand is usually categorized as the content portion of science, focusing on connections between scientific ideas.
The third strand is “Engaging in Scientific Reasoning”. As the search for invertebrates in New York City went on, members of our group came to their own conclusions about invertebrate life, such as their lifestyles, as well as their eating, moving, and reproduction habits. These deductions came naturally during the park visits, and expanded our ability to think and reason about the natural world. Many times, the observations and conclusions we made in the field corresponded with published scientific research. At other times, scientists were able to study these creatures for longer and make more sophisticated summaries of their habits and habitats. In more succinct words, scientific reasoning allows one to think like a scientist by creating theories and sharing them with other like-minded individuals.
The fourth strand is “Reflecting on Science”. It is about the ways in which new evidence leads to the re-evaluation of old ideas. Research shows that people generally do no have a good idea of how scientific understanding grows and evolves. In fact, a lot of ideas deemed true by scientists may turn out to be completely wrong, as was the case with the luminiferous ether, the fictional medium through which light was once thought to propagate. Documentaries do a good job at presenting the story behind scientific discoveries, like the physics series A Mechanical Universe, which combines rigorous physical formulations with expository historical reenactments. The strand is ever-present in all of science, which is why the abstract is usually one of the first things to appear in a research article.
The penultimate strand is “Using the Tools and Language of Science”. During the BioBlitz, citizen scientists (the students) were presented with an example of what they would be looking for under the stereoscopic, or dissecting microscope. Later on as they were looking for different species, the scientists accompanying them would identify the species by the correct scientific name. The way that the students interacted with each other and the scientific language that they were exposed to are tools that are universal to science and understanding of the world. Without it, we wouldn’t be able to express our ideas to each other, and scientific endeavors would not be as successful as they are.
Using the tools and language of science further allows learners to identify with science, which is the sixth strand: “Identifying with the Scientific Enterprise”. Most children growing up identify the scientist as a solitary middle-aged Caucasian man in a white lab coat toiling away in a laboratory somewhere. This mindset evolves over time, and proponents of informal science learning believe that one of the best ways for kids to mold an identity around science and scientific inquiry is through citizen science projects and other informal learning opportunities. These experiences may lead to interesting hobbies or even careers in the fields of science and applied science.
The goals of our groups’ research were in part to learn more about the invertebrates of New York City, but more importantly to design learning experiences around the six strands that others can enjoy and appreciate. A mini-documentary was conceptualized and produced, as well as a museum exhibit.
Annelids (Earthworms)
The word ‘annelid’ derives from the Latin word for ‘ring’. Indeed, the annelid may be thought of as composed of many small and uniform rings stacked up on one another. This produces visible segments in the animal, known as segmentation. Not only is the outer skin segmented, but so are nearly all of the annelid’s internal body parts. For most people, the characteristic annelid is the earthworm. We will use it in the case study of the Annelid group of Invertebrates.
Locomotion – The earthworm appears streamlined with no obvious sensory organs or appendages (like legs or claws). The outer skin of the earthworm is thin and rather flexible; it is called the cuticle. Beneath the skin is a layer of circular muscles that define the body wall that are also segmented. Between the body wall and the innermost digestive tube is a cavity called the coelom, which is filled with coelomic fluid. This raises an important question about how earthworms can move. One physical characteristic that is helpful is the presence of four pairs of bristles (little hairs) in each segment that may extend or retract. These bristles help by latching on to the surrounding walls. Another important principle is that when the circumference of a segment shrinks, the length of the segment must increases. The coelomic fluid, which is contained within each segment, tends to exert pressure length-wise whenever the muscles contract the body wall. This is the essence of the ‘hydrostatic skeleton’. In such a way, an earthworm may move by reaching out with the head (by shrinking in diameter and increasing its length), grabbing onto the wall with the bristles, and then allowing the squeezed portion of the body to travel down its length in waves. This method of locomotion is called “peristaltic locomotion” (‘peristaltic’ because it resembles the mechanism by which food passes through the human esophagus). Annelids that burrow extensively show an accentuation in their segmentation. Likewise, annelids that do not burrow as much may show reduction or loss of the partitions between adjacent segments.
Feedingm- Earthworms eat by swallowing soil. The soil contains various organic materials, including seeds, decaying plants, eggs, larvae, and the bodies of small animals. In the process of burrowing, the earthworm will deposit its excretions, called castings or vermicompost, around the mouth of the burrow. Whereas the organic components of the soil are absorbed, most of the soil passes through the body. The action of creating burrows exposes soil to the air. This may improve drainage during rainfall and helps plants grow roots deeper in the soil. Feeding also helps produce humus (stable organic matter), which may increase the fertility of soil, and the basic nutrients necessary for plant growth.
Citizen Science: Uncovering the Annelids
An earthworm was found during our groups’ visit to Prospect Park. It lived inside of a decaying tree bark, and was discovered upon removal of the tree’s outer layer. The earthworm moved slowly and deliberately. When it was captured, the earthworm began contracting wildly, aware that it had been trapped. The contractions lasted between 5 and 10 seconds, as the earthworm thrashed about in the plastic cup it was kept in. After the spasms ceased, the earthworm moved very little and its activity declined dramatically. The earthworm was released soon after.
Arthropods
When a person hears the word “animal” they typically think of mammals or reptiles. It would take them a few more seconds thought to recognize that arthropods, which include insects, arachnids and crustaceans, are also, in fact, animals. In addition, the phylum Arthropoda consists of more than 75% of all animal species. Similar to annelids, they have segmented bodies. They also exhibit tagmatization, meaning that their segmented portions are different from each other since they perform specialized functions. The two major classes of arthropods, insects and crustaceans, have three distinct tagmata, or specialized segments: the head, thorax and abdomen. Arthropods have hard exoskeletons called the cuticle. While the cuticle is protective and waterproof, it does not allow for gases to be exchanged from the animal to its surroundings. Since its exoskeleton is waterproof, it also it better adapted for dry habitats since it does not succumb to dehydration by losing water to its surroundings. The cuticle primarily consists of chitin, a protein that is found in many places in nature such as in fungal cell walls. In addition to being thick and protective, the cuticle also has some thin and flexible areas that might form joints with other harder sections of the cuticle. This allows for movement. Another feature of arthropods is the way in which they grow. Once an exoskeleton is formed, the animal is restricted by the rigidity of the cuticle. Instead, arthropods shed their exoskeleton and secrete a new cuticle. However, the cuticle does not harden until the animal has grown. This process is known as molting, or ecdysis. While the cuticle is soft, the arthropod is more vulnerable to predators than before since it lacks its usual hard, protective outer layer and so it seeks a protective habitat during this time. The arthropods molting process is regulated by hormones. Arthropod muscle is entirely striated, whereas most other invertebrates possess primarily smooth muscle. Striated muscle is far more responsive than smooth muscle; the time required for striated muscle to complete a contraction is generally far less than that required for smooth muscle. This allows arthropods to produce the high-speed motions required to fly. Arthropods have open circulatory systems. Instead of having blood vessels that direct where the blood needs to go, the hearth pumps hemolymph, (the arthropod equivalent of blood) into the body cavity. As the heart relaxes, the hemolymph is drawn back into the heart through pores called ostia. Many physical properties, such as the amount and function of different segments, allow us to distinguish between the different arthropod classes: insects, arachnids and crustaceans.
Insects
Insects make up a large fraction of the total species on Earth at around one million species out of eight million. The vast number of species can be attributed to their feeding specializations, dispersal capabilities, and ability to avoid predators by means of flight. Most flowering plants depend on insects to transfer pollen for fertilization. However, insects also transfer diseases that can be harmful to agriculture. Insects can produce a variety of secreted chemicals that can be poisonous or useful to humans. These facts exemplify that insects can be beneficial, despite the stigma that is places around them. Insects are social animals. They live in structured “civilizations” that strive towards keeping the collective in existence.
The most distinct characteristics of insects are their segmented bodies (head, thorax abdomen) and their six legs. On their heads, they have compound eyes. Compound eyes are capable of forming images. They are called compound eyes because they are composed of many individual units. Light is focused on the receptor surfaces, and the animal is able to examine individual components of the image independently. Insects possess a sophisticated enough nervous system to reconstruct the image detected by the sensory system. All three of these criteria are needed to be able to see using compound eyes. Three pairs of legs and two pairs of wings (if they fly) branch from their thorax. Gas exchange is accomplished by means of a tracheal system. One pair of spiracles (an opening for respiration) is found on the thorax, with additional pairs of spiracles located on many of the abdominal segments. Gas exchange between the tissues and the environment is accomplished directly without involvement of the circulatory system.
A key component of the evolution of insects is the ability of some of them to fly. This allows them to escape predators. Many of their unique features contribute to their ability to fly. Striated muscle allows for rapid, strong movements. Insects have very small, lightweight bodies. Their waterproof exoskeletons prevent dehydration. Open circulatory and efficient gas exchange systems speedily provide muscles with the needed nutrients. Their highly sensitized nervous systems allow them to steer, navigate, detect wind directions, and to locate food and mates. Flying insects also depict asynchronous flight, or their ability to move muscles multiple times from a single nerve signal, which allows them to have sophisticated control over flight.
Citizen Science: Uncovering the Insects
Insects were found on almost every group outing. The most common insects were the ants, commonly seen crawling about in the soil. Termites were observed in large quantities beneath the outer covering of trees. Termites are similar in appearance to ants, but they have straight antennae, while ants have bent antennae. An American Dagger Moth was observed in Prospect Park during the summer. This is a yellow caterpillar with long, black antennae protruding from the anterior, midsection, and posterior of the body. A white ladybug with black spots was observed in the Ramble of Central Park. What seemed to be a miniature, white grasshopper was also observed in the Ramble.
Brooklyn College Library – Insect
American Dagger Moth – Prospect Park
White Ladybug – Central Park
Arachnids (Spiders)
A subphylum of arthropods is the chelicerata (“claw-horn”), which includes horseshoe crabs, scorpions, spiders, etc. They are characterized as being the only group of arthropods that lack antennae. The first anterior segment does not bear any appendages. The second anterior segment bears a pair of clawed appendages (chelicerae) adjacent to the mouth, which are used for grabbing and shredding food. Chelicerata lack mandibles, appendages found adjacent to the mouth in other arthropod groups that are used for chewing and grinding food during ingestion.
Arachnids make up a large class in the chelicerata subphylum. Arachnids include spiders, scorpions, ticks, mites, etc. While the earlier ancestors of the arachnids were marine animals, today they are primarily terrestrial. There are more than 50,000 known species of arachnids. Most arachnids are parasitic and carnivorous predators. Mites and ticks are parasites of animals and plants alike in order to sustain their nutritional needs. Arachnids have a fused head and thorax and thus they have only two body segments. They many have anywhere from no eyes to four pairs of eyes. As opposed to crustaceans and insects, arachnids do not have compound eyes; rather, they have simple eyes. The anterior-most pair of appendages in arachnids is chelicerae, or sharp pincers or fangs that tear apart food prior to digestion. The next pair of appendages are the pedipalps, which are short leg-like sensory appendages modified for grabbing, killing, or reproducing. In spiders, the mature male’s pedipalps are used for transferring sperm to the female.
Following the pedipalps are four pairs of walking legs. Spiders have 3-4 pairs of small abdominal appendages called spinnerets, located near the anus. They are connected to internal glands that secrete proteins to form silk. Silk is used to form safety lines during climbing, for webs to trap prey, to build homes, to mate, and to protect developing young. The chemical composition of silk varies according to what the silk will be used for. The spider can locate prey stuck in its web by feeling the prey tug on the web. The spider can distinguish the movements of different kinds of prey, and acts accordingly. After the spider’s prey is captured in its web, the spider uses its sharp fangs to subdue and paralyze the prey by injecting a poison.
Spiders can survive long periods of time without food, but not without water. Their exoskeleton, as with insects, prevents the moisture of the inner tissues from leaving the body. Water is lost from the body through respiratory exchange and excretion. Water loss is minimized since the respiratory systems are only open to the outside through narrow slits or pores. The spider excretory system consists of tubes that open into the intestine and excrete nitrogen. Many spiders also have excretory organs that open near the base of the legs.
Citizen Science: Uncovering the Arachnids
Spiders were one of the first invertebrate groups spotted during the Citizen Science Project. The first indications of arachnids were the silken sacs hanging under an enclave in a tree near the New York City Marathon finish line. Closer inspection revealed a multitude of miniature spiders crawling about. They could not have been more than a millimeter in length. Evidence of spiders was present in all areas of the park, and spider webs could be seen almost everywhere there were rocks or trees.
Little Spiders and Silk Sacs – Central Park
Crustaceans (Isopods)
The Woodlice (also known as pillbugs) are a subset of the Isopods that have adapted to life on land. They are relatively large organisms (1.2-30 mm in length), and their bodies appear to be flattened height wise. They are widespread and easily identified as an important decomposer in communities. Their diet consists of decaying organic material, including leaf litter, decayed wood, fungi, and bacteria. Research has shown that woodlice may be predatory and have fed on insect larvae. Vertebrates like birds, frogs, and lizards hunt them, as well as some invertebrates like spiders, scorpions, centipedes, and ground beetles. It may be possible to use the woodlice as bio-indicators – that is, to aid in determining the health of an community, based on the following observations: Isopods respond to environmental contamination with increased mortality. They have structures called lysosomes where heavy metals like copper, zinc, lead, and cadmium may accumulate. These traits may help Isopods serve as indicators of pollutants in the environment. Evidence has already been shown that Isopods are useful for monitoring heavy metal pollution in urban areas. Because of their place in the food web, the accumulation of heavy metals may cascade down the food chain and amplify in its severity.
Terrestrial isopods are considered to have been the most successful crustacean colonizers of land. There are about 3700 known species of terrestrial isopods, with a geographical distribution that is centered on Southern and Western Europe, with a decrease in species richness toward the north. Studies have shown that the terrestrial isopods are pretty diverse. During their adaptation, terrestrial isopods developed solutions to the tasks of reproduction, respiration, excretion, and protection from drying as applied to terrestrial life. Some of the most outstanding adaptions to land that terrestrial isopods have compared to their marine relatives are: reduction in size, a water-proof cuticle, an increase in the number of surface structures, pleodopodal lungs (the pleodopods are the swimming limbs of a crustacean), a water conducting system, and a closed brood pouch for holding developing eggs and embryos.
It is intriguing that we can find isopods as if they are still in the process of adapting from sea to land. Isopods have been found on beach, grassland, woodland, the desert, and even in the water. All of this implies that isopods have various degrees of adaptive traits that allow them to thrive in a variety of climates. Below is a short summary of some of their adaptations for settling on land. [Warburg]
Respiration – Isopods carry a wide range of respiratory organs. The marine species have gills and some terrestrial isopods have lung-like structures. Isopods may be able to open and close their respiratory passageways, which may have been one of the key reasons for their success on land.
Reproduction – There are two main structures that are part of their reproductive system. The marsupium is a brood pouch found in many crustacean groups. The marsupial cavity is filled with a fluid and a mucus mass, which surrounds eggs and embryos. It has been found that the fluid has limited nourishment value; egg development may continue despite starvation of the mother. There are also crystals in the fluid, which may be the product of catabolism by developing embryos. [Warburg]
The egg of the Isopod contains two kinds of yolk: a mitochondria yolk around the nucleus and a Golgi yolk, which is evenly distributed. The embryo secretes five successive embryonic envelopes, or sacs, which is indicative of the molting, or ecdysis, that is characteristic of all arthropods. [Warburg]
Behavioral Adaptations – 38 species of Isopods have had their behavioral traits studied. Some findings include their ability to orient their movements and navigate toward their burrow. Isopods can maintain a social structure based on the family unit.
When studying behavior, researchers may focus on simple responses in isopods, such as chemoreception (reaction to smells), hygroreaction (reaction to the humidity of the air), photoreaction (reaction to light), and thermoreaction (reaction to heat). Studies have shown that Isopods respond to their own specific smells. The chemical sensors are located on the antennae. There may be as many as 100 specialized sensory hairs on the antennal tip of Ligia oceanica. [Warburg]
Isopods’ reaction to light is affected by temperature. The Armadillidium vulgare and a number of isopods from the Mediterranean are positively photokinetic (movement in reaction to light) at low and medium temperatures. On the other hand, the desert isopod Venezillo arizonicus is photonegative except at high temperatures.
Other studies were done to see how isopods orient themselves in their habitat. Specifically, the beach isopod Tylos latreille orients itself towards the sea, and may even be able to perceive both height and relative distance. When waves advance, the species Tylos granulatus turns sideways and moves to a higher part of the shore. The isopods can most likely sense wave vibrations through receptors in their antennae.
Citizen Science: Uncovering the Crustaceans
Isopods were found both in Central Park and Prospect Park. They tend to scurry away into the shadow when uncovered, and if they are in any way disturbed, the isopods roll up into a ball, just like an armadillo. They were found on three occasions: twice in Central Park and once in Prospect Park. Based on the structure and design of their outer exoskeleton, it appears as though each was a unique species. They were some of the more interesting invertebrates to be found because of their locomotion and their novelty.
Education
Documentary
The mini-documentary on invertebrates utilizes all six strands of informal science learning in order to fully engage viewers, impart knowledge upon them, and inspire them to pursue further research in the field of entomology.
Strand 1 of informal learning, sparking interest and excitement, is employed early during the video in order to grab attention. A flashy intro with exciting music, followed by a fun-fact question about invertebrates is intended to surprise the viewer and make the video interactive. Most people don’t know that invertebrates make up 97% of the organisms in the Animalia kingdom. “I would’ve assumed mammals are the dominant species in Animalia. Because when I think of animals, I think of dogs, cats, elephants, you know? But this puts a new perspective on things,” said a sophomore from Queens College. Like this student, most people relate their past experiences to what is being learned in order to make sense of new information. When the two forms of information contrast each other (juxtaposition), cognitive dissonance is created, sparking curiosity. Once this curiosity is sparked, it is safe to begin teaching viewers about invertebrates in more detail without losing their interest.
The video proceeds to introduce concepts such as taxonomy. It provides an explanation for the terminology used by scientists, and why this terminology and classification system is necessary. This description applies strands 2 and 5 simultaneously. Scientific concepts and language are explained. This knowledge serves as a foundation upon which all future information in the video builds upon. In effect, this video functions to hold the viewers’ hands as we walk them through the knowledge that we had to learn ourselves.
Strands 3 and 4 are used during the “vlog” portion of the documentary, in which we gather observations of the various invertebrates we find and reflect on them. Noting things such as their scarcity in manmade areas and their abundance in organic material serves as an analysis of the observations, with the video doing much of the thinking for the viewer. As a result, the viewer can get a sense of the scientific method being put to use without having to strain to comprehend the jargon that is often used in other science settings.
The viewer can identify himself as a scientist when the documentary reveals that all of this was part of a citizen science project on iNaturalist, which is a type of project where even the layman can contribute to scientific knowledge and even gain some himself. This is where strand 6 is used. It is vital for the viewer to understand that science learning isn’t designed for an exclusive group, and that they can partake and even contribute to it themselves. The video reminds viewers of this in the end when it mentions exploring the outdoors, just as our group did, in order to gain some insight into nature.
Conclusion
This research shows the effectiveness of citizen science projects. Supplemented with information from scientific journals and other authoritative publications, citizen science rivals formal learning in both breadth and depth. These projects could be incorporated into a formal science curriculum to encourage students to enter careers in science and engineering or at the very least, begin hobbies of a scientific nature. A citizen science project can develop curiosity, scientific inquiry, and reasoning skills in a child, which are all traits we need for our future scientists.
References
Buchsbaum, Ralph, Mildred Buchsbaum, John Pearse, and Vicki Pearse. Animals Without Backbones: An Introduction to the Invertebrates. 3rd ed. Chicago: University of Chicago Press, 1987. Print.
Pechenik, Jan A. Biology of the Invertebrates. Boston: Prindle, Weber & Schmidt, 1985. Print.
Fenichel, Marilyn, and Heidi A. Schweingruber. Surrounded by Science: Learning Science in Informal Environments. Washington: National Academies Press, 2010. Web.
May, Robert M. “How Many Species Are There on Earth?” Science, 1988. Print.
Warburg, M. R. “Isopods and Their Terrestrial Environment.” Advances in Ecological Research, Volume 17. London; New York; Academic Press. 1987. Print.
Paoletti, Maurizio G. and Hassall, Mark. “Woodlice (Isopoda: Oniscidea): their potential for assessing sustainability and use as bioindicators.” Agriculture, Ecosystems and Environment 74. Elsevier, 1999. Print.
Hornung, Elisabeth. “Evolutionary adaptation of oniscidean isopods to terrestrial life: Structure, physiology and behavior.” Terrestrial Arthropod Reviews 4. Brill, 2011. Print.
Kooch, Yahya and Hamid Jalilvand. “Earthworms as Ecosystem Engineers and the Most Important Detritivors in Forest Soils.” Pakistan Journal of Biological Sciences 11. Asian Network for Scientific Information, 2008. Print.
