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Hyperolius marmoratus

By Jessica High

Geographic Range

Hyperolius marmoratus is widely distributed in sub-Saharan Africa. (Channing, 2001)

Habitat

Hyperolius marmoratus is found in savannas and open bush along water sources such as rivers and streams, as well as in lowlands that contain temporary pools during the rainy season. (Channing, 2001)

  • Aquatic Biomes
  • rivers and streams
  • temporary pools

Physical Description

Hyperolius marmoratus is small to medium in size, the male reaching 43mm in length. The side of its snout is curved and the head width is 32-38% of its body length. The toes end in toe pads that enable the frog to climb up stems of grass and reeds. They have an enormous variety of brightly colored markings, with a profusion of stripes, spots, or stippling. Currently, populations are grouped by shared color patterns into subspecies. Some may be pale brown with darker spots or striped with lighter and darker brown. Others may be striped with thick bands of black and white with a yellow stripe running down the center. While, still others have red-brown spots on a light background. There are many variations known. ("Survival Online", 2001; Channing, 2001)

  • Sexual Dimorphism
  • sexes alike
  • Range length
    43 (high) mm
    1.69 (high) in

Development

Hyperolius marmoratus tadpoles hatch in less than a week and develop into small froglets within 2 months. Tadpoles may grow to be 44mm in length. They are brown with speckled fins, and have tails that end in a sharp point tipped with black. The tadpoles are bottom dwellers, and prefer shallow, grassy pools. In captivity, metamorphosis takes 64-100 days. The adult color phase develops when the frog reaches sexual maturity. The identification of Hyperolius marmoratus depends largely on color pattern. (Channing, 2001)

Reproduction

Males establish small calling territories in ponds in order to breed. Elevated calling sites are defended through intense kicking bouts against any male intruders. Hyperolius marmoratus females approach males in breeding ponds and initiate amplexus. (Channing, 2001)

This lasts for several hours making it possible for a male to mate with only one female each night. Fertilization is external during the period of egg laying. A Hyperolius marmoratus clutch consists of 150-600 small eggs that are between 1.3-1.5mm in diameter, and are within 2.5mm capsules. The eggs are laid in clumps of about 20, attached to underwater vegetation, during the rainy season. They are pale yellow with a dark brown end, although some have also been reported to be blue-green. In captivity, females are reported to produce eggs every 2 or 3 weeks for up to 14 months or longer, once they reach sexual maturity. In the field this may be variable depending on the weather. ("Survival Online", 2001; "Travel Africa Online", 2002; Channing, 2001; Grafe, 1997; Schmuck, et al., 1994)

  • Breeding interval
    Females may produce eggs every 2 to 3 weeks.
  • Breeding season
    Breeding seasons last from the first rains of spring to late summer.
  • Range number of offspring
    150 to 650
  • Average number of offspring
    300-400
  • Average time to hatching
    5 days

Neither sex provides parental care. (Channing, 2001)

  • Parental Investment
  • no parental involvement
  • pre-fertilization
    • provisioning
    • protecting
      • female

Lifespan/Longevity

In captivity Hyperolius marmoratus can live at least 4 years 9 months. (Channing, 2001)

  • Typical lifespan
    Status: captivity
    4.75 (high) years

Behavior

Hyperolius marmoratus is highly terrestrial and returns to water only to breed. They spend much of the day sitting motionless on reeds and other waterside plants, while at night they become more active and the males begin to call. During the heart of the dry season H. marmoratus entirely suppresses feeding, and its survival time depends both on energy reserves and on its ability to minimize evaporative water loss. ("Survival Online", 2001; Grafe, 1997; Schmuck and Linsenmair, 1997)

Hyperolius marmoratus spends much time exposed to the bright sun, putting it at risk from drying out. Yet it still has a very low rate of water loss through the skin compared with other frogs. Water is conserved by H. marmoratus in three ways. First, it has a "water balance" response in which it reduces activity and rests in a water-conserving posture that minimizes surface exposure. During the dry season it remains motionless on a single leaf throughout the day. It also aestivates, which is a special form of dry season "hibernation." This slows down its metabolism to 50% of its normal resting rate. Also during the dry season, especially during high temperatures, H. marmoratus is white and therefore reflects sunlight. This color comes from the food that H. marmoratus consumes. Food wastes are converted into substances called purines. Small purine platelets arranged parallel to the surface are part of the pigment cells, or iridiophores, of the skin. These crystals act as interference reflectors, and reduce the heat load by reflecting sunlight. Lastly, H. marmoratus becomes completely anuric when dehydrated. Because of this it is able to store water in the bladder which can be used later for cooling when conditions become harsh. Above very high temperatures it makes use of this water by releasing it through the skin to evaporate and cool itself. Also, H. marmoratus has an accelerated water uptake, which can extend the survival period when dewfall or very short and light occasional rain showers supply a few drops of water at irregular intervals. (Channing, 2001; Schmuck and Linsenmair, 1997)

Home Range

There is no information available on home range in this frog species.

Communication and Perception

Hyperolius marmoratus has an impressive vocal capacity. The male calls from vegetation around bodies of water. The call is a short whistle, only about 0.1 seconds long and has a frequency ranging from 2.8 to 3.1 kHz. The vocal sac of H. marmoratus is very large. This amplifies his call, making it very loud. Two males may call simultaneously, alternating with a third male. The call helps to maintain male spacing to a minimum of about 50 cm. Females prefer to select an isolated male as opposed to a male calling close to another male, as well as a male that is near to the female's release site. Females are also attracted to high call rates and greater intensities. Females select the male with the loudest call, so long as there is a noticeable difference between the calls of that area. It is speculated that females choose conspicuous males in order to reduce search time when under the risk of predation in the chorus. It has been found that chorus tenure duration has the most significant influence on mating success. Because calling is energetically expensive to H. marmoratus, by mating, males are able to conserve energy, which enables them to attend the breeding site more frequently and to call more energetically. Males will also return on successive evenings to exactly the same calling site. ("Travel Africa Online", 2002; Channing, 2001; Dyson, et al., 1998; Grafe, 1997)

Touch is used to initiate amplexus. These frogs also perceive the environment with their keen eyesight, attuned to perceiving motion.

Food Habits

Hyperolius marmoratus feeds on a variety of small insects. (Channing, 2001)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods

Predation

Hyperolius marmoratus adults rely on their agility and ability to leap great distances to escape from danger. They also have red skin on the inside of the thighs and the side of the belly, which functions as a startle mechanism, because it is only visible when the animal jumps. ("Survival Online", 2001; "Travel Africa Online", 2002; Channing, 2001; Grafe, 1997)

Ecosystem Roles

Hyperolius marmoratus is prey to many different species of animals in its ecosystem.

Economic Importance for Humans: Positive

Hyperolius marmoratus is known to be a predator of the important citrus pest, the citrus psylla (Diaphorina citri). (Channing, 2001)

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of these frogs on humans.

Conservation Status

These frogs are widespread and not currently considered threatened. Local populations may be threatened by water diversions, habitat disruption, and pesticide or herbicide use.

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Jessica High (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

choruses

to jointly display, usually with sounds, at the same time as two or more other individuals of the same or different species

duets

to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

freshwater

mainly lives in water that is not salty.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

polyandrous

Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).

polygynous

having more than one female as a mate at one time

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

References

2001. "Survival Online" (On-line). Accessed March 18, 2002 at http://www.tiscali.co.uk/reference/nature/survivalonline/reedfrog.html.

2002. "Travel Africa Online" (On-line). Accessed 11/14/05 at http://www.travelafricamag.com/content/view/711/72/.

Channing, A. 2001. Amphibians of Central and Southern Africa. Ithaca and London: Comstock Publishing Associates - Cornell University Press.

Dyson, M., S. Henzi, T. Halliday, L. Barrett. 1998. Success breeds success in mating male reed frogs (Hyperolius marmoratus). The Royal Society of London, 265: 1417-1420.

Grafe, T. 1997. Costs and benefits of mate choice in the lek-breeding reed frog, Hyperolius marmoratus. Animal Behavior, 53: 1103-1117.

Schmuck, R., W. Geise, K. Linsenmair. 1994. Life cycle strategies and physiological adjusments of reedfrog tadpoles (Amphibia, anura, hyperoliidae) in relation to environmental conditions. Copeia, 4: 996-1007.

Schmuck, R., K. Linsenmair. 1997. Regulation of body water balance in reedfrogs (superspecies Hyperolius viridiflavus and Hyperolius marmoratus: Amphibia, anura, hypeoliidae) living in unpredictably varying savannah environments. Comparative Biochemistry and Physiology, 118A (4): 1335-1352.

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