Weirdly, a decapitated planarian body can detect light, and many planarian species have ear-like structures on their heads that don't detect sound but chemicals; you could say that they taste and smell with their ears. 5. There was an actual comic book titled Planarian Man. Neal Obermeyer
Do planarians have eyes or ears?
There are also species with many eyes, distributed throughout their bodies; species with only one eye; and eyeless species. Weirdly, a decapitated planarian body can detect light, and many planarian species have ear-like structures on their heads that don't detect sound but chemicals; you could say that they taste and smell with their ears.
Can planarians smell?
Weirdly, a decapitated planarian body can detect light, and many planarian species have ear-like structures on their heads that don't detect sound but chemicals; you could say that they taste and smell with their ears. 5. There was an actual comic book titled Planarian Man.
Do Planaria eat poop?
The remains of plants and animals and even poop – are all tasty meals for these planaria. On the other hand, some planaria are successful predators and hunt for worms, snails, and small arthropods, such as daphnia, isopods, and baby shrimps. Planarian eats by sucking up food (could be live or dead small animals) with its muscular mouth.
Do planarians have memory?
Planarians are capable of learning, and upon decapitation, the bodies with newly regenerated heads will remember what they learned. In the 1950s and 1960s, experimental psychologist James V. McConnell and collaborators did a series of experiments using planarians to explore memory processes.
What senses do planarians have?
Additionally, the planarian has two visible sensory organs. The auricles are lateral flaps near the anterior of the animal. The auricles are chemoreceptors and sense chemicals in the water. Also near the anterior are two eyespots.
Can flatworms hear?
elegans — such as flatworms, earthworms and mollusks — might also be able to sense sound. “Our study shows that we cannot just assume that organisms that lack ears cannot sense sound,” says Xu, who is also a professor of molecular and integrative physiology at the U-M Medical School.
Can worms hear sound?
Instead, new experiments have revealed, its skin doubles as a sound-sensing membrane, effectively making the worm's entire body an eardrum. This study, detailed recently in the journal Neuron, presents the first evidence ever found that a non-arthropod invertebrate can sense airborne sound.
Can planarians sense light?
Planarians sense visible light through their cerebral eye. On the other hand, UV light sensing (extraocular) is dispersed throughout the planarian body.
Do worms feel pain?
But a team of Swedish researchers has uncovered evidence that worms do indeed feel pain, and that worms have developed a chemical system similar to that of human beings to protect themselves from it.
Can worms listen to music?
“Worms do not possess any sense of hearing,” Darwin wrote. “They took not the least notice of the shrill notes from a metal whistle, which was repeatedly sounded near them; nor did they of the deepest and loudest notes of a bassoon.
Can worms hear or see?
Sensory Lack Worms have no external ears, so their sense of touch and vibration receptors compensate for their lack of hearing. Worms also have no eyes, so they cannot see their surroundings. This puts worms at a disadvantage when they are above ground and cannot feel their surroundings as well.
Do worms have voices?
The Worms have different voices and can be customized in most games. Players can change their teams' accents in the Manage Teams subsection. During gameplay, the Worm in the team will speak catchphrases before doing anything.
Do worms have genders?
Earthworms are hermaphrodites, meaning an individual worm has both male and female reproductive organs. Earthworm mating typically occurs after it has rained and the ground is wet. They emerge from the soil and jut out their anterior end.
Do Planaria like light or dark?
Background. Planarians, like rodents, instinctively spend more time in dark versus light environments when given a choice. This behavioral phenomenon is called negative phototaxis, which may reflect defensive responding related to an anxiety-like phenotype.
Can Planaria see color?
Planarians have simple, cup-shaped eyes with a single type of photoreceptor. This means that they are colour blind, and can only view the world in grey. Dr.
Do Planaria have eyes?
Although the planarian eye is far simpler than a human eye, there are significant similarities. The planarian eye is composed of a pigmented cell cup and photoreceptor cells, which extend rhabdomeres into the eye cup. These photoreceptors have axons that project directly to the visual center of the planarian brain.
What do flatworms do to humans?
Children who are repeatedly infected can develop anemia, malnutrition and learning difficulties. After years of infection, the parasite can damage the liver, intestine, lungs and bladder. Rarely, it can also cause seizures, paralysis or spinal cord inflammation.
Can flatworms live in humans?
There are a variety of parasitic worms that can take up residence in humans. Among them are flatworms, roundworms, and thorny-headed worms (spiny-headed worms). The risk of parasitic worm infection is higher in rural or developing regions.
Is flatworms useful or harmful?
Flatworms can be harmful to humans. These are generally endoparasites that cause numerous diseases. Taeniasis, an intestinal infection, is caused by parasitic flatworms viz. Taenia solium, Taenia saginata, and Taenia asiatica.
What eats flat worms?
Flatworms have a number of natural predators, including the Sixline Wrasse (Pseudocheilinus hexataenia), the Yellow Wrasse, and the Spotted Mandarin. The biggest drawback to ridding your tank of flatworms with this method is that the fish will not consume every flatworm in the tank.
What does a planarian look like?
Planaria come in a wide range of colors, sizes, and head shapes. The most frequently used planarian in the classrooms and laboratories is the brownish Girardia tigrina. Other common species used are the blackish Planaria maculata and Girardia dorotocephala. Recently, Schmidtea mediterranea also becomes a popular model organism for molecular biological and genomic research.
How do Planaria move?
Planaria move across a surface using cilia on their ventral (meaning belly) surface. They can secrete a film of gel-like mucus to serve as a lubricant. They also move by contracting their muscles to swim with an undulating motion or creep like slugs. These muscles are controlled and coordinated by the nerve cords.
What do Planaria eyespots use to detect?
These eyespots consist of photoreceptor cells that can detect the intensity of light. Planaria use their eyes to move away from bright light sources.
How many eyes do planarians have?
Some planarian species have two eyespots (also known as ocelli). It is funny since it looks like the planarian has cross-eyes. However, some species may have several eye spots. For example, one species, Polycelis felina, even has over 20 eyes.
What is the phylum of flatworms?
The phylum Platyhelminthes includes flatworms. “Platy” means flat and “helminth” means worm. They can be divided into three major categories: (1) Turbellaria: free-living flatworms, like Planarian (in freshwater) and Divided flatworm (in marine); (2) Trematoda: parasitic flukes that Infect internal organs of a host. Ex. Schistosoma fluke causes Schistosomiasis – fluke’s eggs clog blood vessels of patients; (3) Cestoda: parasitic tapeworms, like pork and beef tapeworms, that have a snake-like long body and a head with suckers/hooks to attach to intestinal walls of a host.
How many stimuli can Planaria sense?
Planaria can sense and respond to at least three forms of stimuli:
How big do planarians get?
The length of a planarian is usually about 3 to 15 mm (0.1 to 0.6 inches); some can grow up to 30 cm (about 1 foot) long.
What is a bipalium kewense?
Bipalium kewense is a large, conspicuous flatworm reaching up to 17 cm or more in length, with a pronounced lunate or spade-like head. It is brightly marked with five dark brown stripes running the length of the body on a light brown or olivaceous background. Bipalium kewense cannot survive submersion in water. In addition, collection of a possible third land planarian believed it to be Geoplana vaga was made in Arkansas. However, upon further microscopic examination of the genitalia of this 6.5 cm (2.6 in.) specimen, it did not match the description of G. plana, suggesting it might have been an undescribed species. To date, the exact identity of this specimen has not been resolved.
What are the two types of planarians in Arkansas?
In Arkansas, there are both terrestrial and freshwater planarians. To date, only two land planarians have been reported from Arkansas. A single specimen of Microplana atrocyaneus was collected at Stair (Marion County) in 1942, while Bipalium kewense was first reported in 1976. Land planarians in the state are generally long (up to 170 mm [6.7 in.]), slender flatworms found in moist, dark habitats such as under boards, concrete slabs, and logs, and in leaf mold. These organisms are thought to be among the most primitive metazoans that can live successfully in a terrestrial environment. However, they require high humidity since prolonged exposure to air presents a danger of dehydration. Planarians secrete a protective mucus slime coat that prevents dehydration and can be seen as a slime trail marking the flatworm’s previous route on land.
How do planarians reproduce?
They have well-developed gonads, ducts, and accessory organs. Most planarians are hermaphroditic (monoecious) and reproduce by fission , but cross fertilization (sexual reproduction) is possible between two specimens. Freshwater planarians can reproduce asexually simply by constricting behind the pharynx and separating in two individuals (zooids), each of which can regenerate missing portions. After copulation, one or more fertilized eggs and some yolk cells become enclosed within a small cocoon (hard capsule) that is attached by little stalks to the underside of rocks or plants. In some species, the yolk for nutrition in the developing embryo is endolecithal (contained within the egg cell itself)—an ancestral condition for flatworms. The development of the embryo is via spiral determinate cleavage. Emerging embryos are already juveniles that resemble larger mature adults. Some marine forms possess embryos that develop into a ciliated free-swimming larva.
Where can I find Planarians in Arkansas?
kewense, which has been found a number of times in Arkansas, primarily in greenhouse situations or private residences. Bipalium kewense is easily identified by its diagnostic spade-like head and bi-colored body. It is known from Ashley, Chicot, Clark, Columbia, Dallas, Faulkner, Jefferson, Miller, Ouachita, Polk, Pope, Pulaski, and Union counties. Although native to tropical Asia, land planarians have been dispersed via the trade in tropical plants; thus they commonly are observed in greenhouses in the soil of potted plants and have become established across the southern United States. They are often found after heavy rains on driveways or sidewalks, although specimens have been discovered under wet boards, logs, rotting trees, railroad ties, and concrete patio slabs. The establishment of B. kewense is of concern because it can be detrimental to populations of earthworms, on which they feed by apparently using a neurotoxin (tetrodotoxin) for paralysis.
Where are planarians found?
There are at least seven species of planarians found in Arkansas, on land and in water. Planarians belong to the superphylum Lophotrochozoa, phylum Platyhelminthes, subphylum Catenulidea, class Rhabditophora (some consider the artificial grouping Turbellaria), order Tricladida, suborder Paludicola, and families Dugesiidae, Kenkiidae, Planariidae, and Dendrocoelidae. These flatworms are often simply referred to as triclads or triclad worms. Currently, the order Tricladida is split into three suborders, including the marine forms (Maricola); those found mostly in freshwater habitats of caves, although at least one species occurs in surface waters (Cavernicola); and land planarians/freshwater triclads (Continenticola). Scientists have argued about the systematics of platyhelminths for many years, and with the advent of molecular approaches (18S and 28S ribosomal DNA sequences), older classification schemes are being reconsidered, particularly among “turbellarians.” Indeed, not all taxonomists agree upon any one classification or the phylogenetic relationships among the various taxa.
Where do planarians live in Arkansas?
Freshwater planarians occur throughout Arkansas in favorable habitat and include the following: Cura foremanii from streams in the Interior Highlands and Gulf Coastal Plain; Dendrocoelopsis americana from Logan, Polk, and Washington counties; D. dorotocephala from seventeen counties; Girardia tigrina, the most common Arkansas planarian, which occurs in at least twenty-three counties; an immature Phagocata sp. from Cleburne, Izard, and Lawrence counties; P. gracilis from five counties; and Proctyla fluviatilis from Crittenden County. They prefer springs, seeps, caves, and other fishless areas. Interestingly, while several flatworms have been found in Arkansas caves, only a single species, D. americana, may be considered a cave obligate (troglobitic) species. It is considered critically imperiled (S1) in Arkansas and also occurs in Missouri and Oklahoma caves. In addition, a number of populations of D. americana are forms possessing eyes, but an eyeless population was reported from a well in Texas. An unidentified cave triclad flatworm from a cave in the Sylamore Ranger District and in three caves in the Buffalo National River, and P. gracilis from Rowland Cave ( Stone County ), were reported in Arkansas but, to date, the former had not yet been identified. Reports of cave flatworms are not well known from the state but may simply reflect minimal collecting effort rather than the lack of species.
Who was the first biologist to study planarians?
One of the most famous biologists to study planarians was Libbie Henrietta Hyman (1888‒1969). She published her first group of papers on planarians while at the University of Chicago, and many more were published during her career. Another biologist, Roman Kenk (1898–1988) of the Smithsonian Institution, also provided a great deal of taxonomic information on North American planarians. He described more than thirty Nearctic species, and a Nearctic family (Kenkiidae) and genus ( Kenkia) of planarians were named in his honor.
What can planarians tell us about ourselves?
Planarians should thus facilitate analysis of the mechanisms by which cell–cell interactions specify germ cell fates. Despite the importance of tissue homeostatic processes to human biology and health (humans are estimated to lose ∼10 billion cells per day), relatively little is known about how tissue homeostasis is controlled. Adult planarians constantly replace their tissues during normal cell turnover, so they provide an experimental paradigm in which to study such homeostatic processes. The long lifespan of planarians and the way they use stem cells to replace aged tissues should aid the identification of genes that regulate the rate at which cells are lost through cell death, and those that promote longevity by controlling cell replacement. Finally, the robust and complex behavioral responses of planarians to stimuli, combined with modern methodologies for studying gene function, means that planarians should be a good system for studying the neural control of learning, memory, social behavior, chemotaxis, rheotaxis and geotropism.
How do planarians reproduce?
They reproduce sexually or asexually. Sexual animals are hermaphrodites unable to self fertilize, while asexual animals undergo transverse fission posterior to the pharyngeal opening. The embryogenesis of freshwater planarians is equally intriguing: cleavage of the fertilized egg was described as ‘anarchic’ by early developmental biologists. No overt gastrulation or epiboly has been described in these embryos, yet they manage to develop anteroposterior and dorsoventral axes without difficulty. Not bad for an animal usually regarded as ‘simple’.
How many stages of regeneration are there in Planarian S. mediterranea?
Figure 1 The planarian S. mediterranea (top) and three stages of head regeneration (bottom). The numbers are days after amputation. (Scale bar, 650 μm.)
What are neoblasts?
What are neoblasts? Small, highly undifferentiated cells with large nuclei and very little cytoplasm, distributed throughout the body of an adult planarian. They are the only mitotically active cells in planarians, and so are responsible for the cell proliferation observed in both intact and amputated animals. They constitute 25–30% of all planarian cells, and have been shown to differentiate into epidermis, muscle, neurons and germ cells, among others. Self-renewing neoblasts are regarded as stem cells and are being used to identify and test mechanisms that regulate stem cell activities in metazoans.
What is the Schmidtea database?
The Schmidtea mediterranea database as a molecular resource for studying platyhelminthes, stem cells and regeneration.
What is a planarian?
What are planarians? As any high school student will tell you, planarians are flat, free-living worms, members of the phylum Platyhelminthes (Platy, flat; helminth, worm) with cross-eyed-looking photoreceptors and a remarkable capacity for regeneration ( Figure 1 ). The regenerative prowess of planarians has been known for centuries: Dalyell wrote in 1814 that planarians appear to be “immortal under the edge of the knife”.
What is the smallest fragment that can regenerate a complete worm?
What is the smallest fragment that can regenerate a complete worm? According to T.H. Morgan, a lateral fragment 1/279 th the size of the original worm. This corresponds to about 10,000 cells. If you consider that such a small fragment now has the job of re-specifying its body midline to regain bilateral symmetry, while simultaneously preserving anteroposterior and dorsoventral polarities and resetting these axes to their appropriate positional values, it is easy to see why planarians have captured the imagination of generations of biologists.
What phylum are flatworms in?
Here’s the technical bit—within the phylum Platyhelminthes is the Cclass Turbellaria (the non-parasitic guys). Most turbellarians are small—less than an inch long—and many are microscopic. class Turbellaria is broken down into several orders, some of whose members only live in salt water, but two orders of flatworms that live in fresh water are Tricladida and Rhabdocoella. Tricladida have fancy, three-branched guts (gastrovascular cavities) and are referred to by those in the inner circles as triclads or planarians, and Rhabdocoela have simple guts and are called Rhabdocoels, or, loosely, planarians. Flatworms are not related to segmented worms like earthworms and leeches, though they are often mistaken for leeches.
Why are planarians green?
The BugLady is completely enthralled by these small (4 or 5mm), bright green, ephemeral pond planarians, and it turns out that their story rates a “10” on the Wowsers Scale. She thinks that these rhabdocoels are in the genus Dalyellia , possibly Dalyellia viridis, though some other genera get green, too. Apparently, the green color is due to algae that exist, grow, photosynthesize and reproduce within the planarian’s tissues. Planarians may ingest the algae and/or it may be a gift from their Mom/Dad, deposited in the eggs. Green planarians tend their gardens well — they are more sun-loving than their brown-gray-black-mottled cousins.
What are the critters in the Ephemeral Pond?
Among the critters that the BugLady has been seeing in the Ephemeral Pond lately have been a variety of flatworms that are generally called planarians . The majority of members of the phylum Platyhelminthes (the flatworms—a phylum that includes the notorious tapeworms and flukes) are parasitic; planarians are labeled the only free-living (non-parasitic) flatworms in the bunch. Planarians are easily overlooked, but amazing, critters. Although they have only primitive brains, planarians can learn; some have green thumbs; and because of their super-powers, they may have a leg up on this “immortality” thing.
How do planarians run mazes?
Using light and tiny electric shocks, scientists have taught or conditioned planarians to run mazes. If a trained planarian is cut in pieces, most sections remember the way through the maze after they’ve regenerated (but grinding up trained planarians and feeding them to other planarians does not transmit memory) (it’s been tried).
Why are flatworms so small?
A generic flatworm is small and flat because it doesn’t have lungs or blood vessels to circulate oxygen and nutrients —when stuff simply diffuses through your body, you just can’t afford to grow very big, or thick, or complex. It is bilaterally symmetrical—its right side matches its left side. While some marine flatworms are pretty flashy, their freshwater cousins tend to be drab, camouflaged among the aquatic plants and the debris on the pond or stream floor. Many species have a recognizable arrow-shaped head with pointy flaps that stick out like tiny ears, and two spots that look like crossed eyes. The mouth is located at the tip of a small, hose-like tube (the pharynx) that tucks into the gastrovascular cavity in the middle of the flatworm’s underside. Food enters, and wastes exit, through the same tube. It breathes through its outer covering (epidermis).
How many tails does a planarian have?
Some planarian trivia: the sperm cells of most species of planarians have two tails instead of the almost-universal single tail.
What is a turbellarian?
A turbellarian’s outside, especially its underside, is covered with fine, hair-like cilia. Moving from Point A to Point B involves producing a layer of mucous that covers the body and then using the movements of the cilia (and muscle waves in larger specimens) to glide along on underwater surfaces, like a snail. Like a snail it can also move, belly up, on the underside of the surface film of the pond, and some species use their cilia to swim. According to Voshell in A Guide to Common Freshwater Invertebrates of North America, “The scientific name Turbellaria came from the Latin word turba meaning confusion, crowd, bustle, or stir. This refers to the minute currents created in the water as flatworms wave the very small hairs on the bottom of their bodies to glide across the substrate.” Mini-currents set in motion by mini-hairs on mini-animals. Wowsers!
Where do I buy planarians?
The planarian species we use can be ordered from Carolina Biological Supply or from Ward's Science. For more details, click on the “Source” tab from within each species page. The species pages can be found in About Our Planarians.
Can the Sánchez Lab send me some reagents?
No, the Sánchez Lab is not providing worms or reagents. All the mentioned worms and materials are commercially available.
How long does the complete regeneration of the worms take?
Worm fragments can completely regenerate by 2 weeks, except P. gracilis whose regeneration requires more than one month.
Where are the protocols for planarian maintenance, planarian regeneration observation, whole mount in situ hybridization and RNA interference?
All the protocols and lists of required materials can be found in the sidebar under Protocols.
What can my students do with common, inexpensive equipment?
The planarian maintenance, feeding and amputation activities can be performed without any specific and/or expensive equipment. These activities are safe for students and teachers. The regeneration of the animals can be followed with a magnifying lens or even a smartphone's camera. For more details, look at Section 1.5: Image acquisition of live worms in the Planarian Maintenance Protocol found in the sidebar.
Where can I find more information about the biological and medical discoveries being made by researchers using planarians?
Here is a list of recent publications from laboratories using planarians to study regeneration and stem cell biology:
Where can I find more information about planarians?
These are a collection of review papers on the topic of planarians and their remarkable biological attributes.