Thysanozoon nigropapillosum

Last updated

Thysanozoon nigropapillosum
Yellow papillae flatworm (Thysanozoon nigropapillosum) (cropped).jpg
Thysanozoon nigropapillosum swimming in Manta Ray Bay, Yap
Scientific classification Red Pencil Icon.png
Domain: Eukaryota
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Rhabditophora
Order: Polycladida
Family: Pseudocerotidae
Genus: Thysanozoon
T. nigropapillosum
Binomial name
Thysanozoon nigropapillosum
(Hyman, 1959) [1]
  • Acanthozoon nigropapillosum Hyman, 1959

Thysanozoon nigropapillosum is a species of polyclad flatworms belonging to the family Pseudocerotidae. Some common names include gold-speckled flatworm, marine flatworm, yellow papillae flatworm, yellow-spotted flatworm, and yellow-spotted polyclad flatworm.



Thysanozoon nigropapillosum has a long body and broad shape. They grow up to 3 in (76 mm). [2] The dorsal surface is deep black and covered with numerous yellow-tipped papillae varying in size. The ventral surface is dark brown. The outer margin of the body is slightly wavy and bordered in opaque white. They have small, ear-like pseudotentacles in the middle of the anterior end. [3] They swim by propelling themselves through the water with a rhythmic undulating motion of the body. [2]


This species is widespread in the tropical Indo-Pacific. [4]


Thysanozoon nigropapillosum is quite common along the external reef in the shallow sub-tidal zone. It can swim by undulating and rhythmically contracting the body margins. It feeds on tunicates, using its mouth and large pharynx to engulf Didemnum spp., and later regurgitates food pellets containing the calcareous spicules present in their tunics. Polyclad flatworms are hermaphrodites, with each one of a pair of flatworms trying to inseminate the other. Transfer of sperm may be by hypodermic insemination, but this is made difficult in this species by the presence of the papillae, and dermal impregnation often occurs. This involves sperm entering the body directly after being placed in the marginal region of the skin. Such dermal insemination is facilitated by the fact that the flatworm has two penises which are strengthened by the presence of rhabdites, and these can grip the margin of the partner and keep hold, even while the recipient is swimming. [5]

Related Research Articles

Amphibian A class of ectothermic tetrapods, which typically breed in water

Amphibians are ectothermic, tetrapod vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arboreal or freshwater aquatic ecosystems. Thus amphibians typically start out as larvae living in water, but some species have developed behavioural adaptations to bypass this.

Salamander Order of amphibians (Urodela)

Salamanders are a group of amphibians typically characterized by a lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All present-day salamander families are grouped together under the order Urodela. Salamander diversity is highest in the Northern Hemisphere and most species are found in the Holarctic realm, with some species present in the Neotropical realm.


Squid are cephalopods in the superorder Decapodiformes with elongated bodies, large eyes, eight arms and two tentacles. Like all other cephalopods, squid have a distinct head, bilateral symmetry, and a mantle. They are mainly soft-bodied, like octopuses, but have a small internal skeleton in the form of a rod-like gladius or pen, made of chitin.

Dragonfly Infraorder of insects with long strong bodies and two pairs of wings

A dragonfly is an insect belonging to the order Odonata, infraorder Anisoptera. Adult dragonflies are characterized by large, multifaceted eyes, two pairs of strong, transparent wings, sometimes with coloured patches, and an elongated body. Dragonflies can be mistaken for the related group, damselflies (Zygoptera), which are similar in structure, though usually lighter in build; however, the wings of most dragonflies are held flat and away from the body, while damselflies hold their wings folded at rest, along or above the abdomen. Dragonflies are agile fliers, while damselflies have a weaker, fluttery flight. Many dragonflies have brilliant iridescent or metallic colours produced by structural colouration, making them conspicuous in flight. An adult dragonfly's compound eyes have nearly 24,000 ommatidia each.

Sexual dimorphism Condition where the two sexes of the same species exhibit different characteristics

Sexual dimorphism is the condition where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organs. The condition occurs in many animals and some plants. Differences may include secondary sex characteristics, size, weight, colour, markings, and may also include behavioral and cognitive differences. These differences may be subtle or exaggerated, and may be subjected to sexual selection and natural selection. The opposite of dimorphism is monomorphism.

Xu (surname) Surname list

Xu is either of two Chinese surnames that are homographs when Romanized using their Mandarin pronunciations:

  1. Chinese: 徐; pinyin: ; Wade–Giles: Hsü2; Jyutping: Ceoi4
  2. simplified Chinese: 许; traditional Chinese: 許; pinyin: ; Wade–Giles: Hsü3; Jyutping: Heoi2
Sperm competition

Sperm competition is the competitive process between spermatozoa of two or more different males to fertilize the same egg during sexual reproduction. Competition can occur when females have multiple potential mating partners. Greater choice and variety of mates increases a female's chance to produce more viable offspring. However, multiple mates for a female means each individual male has decreased chances of producing offspring. Sperm competition is an evolutionary pressure on males, and has led to the development of adaptations to increase males' chance of reproductive success. Sperm competition results in a sexual conflict of interest between males and females. Males have evolved several defensive tactics including: mate-guarding, mating plugs, and releasing toxic seminal substances to reduce female re-mating tendencies to cope with sperm competition. Offensive tactics of sperm competition involve direct interference by one male on the reproductive success of another male, for instance by physically removing another male's sperm prior to mating with a female. For an example, see Gryllus bimaculatus.

Polycladida An order of free-living marine flatworms

The Polycladida represents a highly diverse clade of free-living marine flatworms. They are known from the littoral to the sublittoral zone, and many species are common from coral reefs. Only a few species are found in freshwater habitats.

This glossary of ichthyology is a list of definitions of terms and concepts used in ichthyology, the study of fishes.

Short-tail stingray

The short-tail stingray or smooth stingray is a common species of stingray in the family Dasyatidae. It occurs off southern Africa, typically offshore at a depth of 180–480 m (590–1,570 ft), and off southern Australia and New Zealand, from the intertidal zone to a depth of 156 m (512 ft). It is mostly bottom-dwelling in nature and can be found across a range of habitats from estuaries to reefs, but also frequently will swim into open water. The largest stingray in the world, this heavy-bodied species can grow upwards of 2.1 m (6.9 ft) across and 350 kg (770 lb) in weight. Its plain-colored, diamond-shaped pectoral fin disc is characterized by a lack of dermal denticles even in adults, and white pores beside the head on either side. The body can have colors as well as dark grey or black with rows of white spots along each wing. Its tail is usually shorter than the disc and thick at the base. It is armed with large tubercles and a midline row of large thorns in front of the stinging spine which has the dorsal and ventral fin folds behind.

Cloudy catshark

The cloudy catshark is a common species of catshark, belonging to the family Scyliorhinidae. It is a bottom-dweller that inhabits rocky reefs in the northwestern Pacific Ocean, from the shore to a depth of 320 m (1,050 ft). Growing up to 50 cm (20 in) long, this small, slim shark has a narrow head with a short blunt snout, no grooves between the nostrils and mouth, and furrows on the lower but not the upper jaw. It is also characterized by extremely rough skin and coloration consisting of a series of dark brown saddles along its back and tail, along with various darker and lighter spots in larger individuals.

Yellow stingray

The yellow stingray is a species of stingray in the family Urotrygonidae, found in the tropical western Atlantic Ocean from North Carolina to Trinidad. This bottom-dwelling species inhabits sandy, muddy, or seagrass bottoms in shallow inshore waters, commonly near coral reefs. Reaching no more than 36 cm (14 in) across, the yellow stingray has a round pectoral fin disc and a short tail with a well-developed caudal fin. It has a highly variable but distinctive dorsal color pattern consisting of either light-on-dark or dark-on-light reticulations forming spots and blotches, and can rapidly change the tonality of this coloration to improve its camouflage.

Courtship display

A courtship display is a set of display behaviors in which an animal, usually a male, attempts to attract a mate; the mate exercises choice, so sexual selection acts on the display. These behaviors often include ritualized movement ("dances"), vocalizations, mechanical sound production, or displays of beauty, strength, or agonistic ability.

<i>Pseudobiceros hancockanus</i>

Pseudobiceros hancockanus is a species of hermaphroditic marine flatworm in the family Pseudocerotidae.

External morphology of Lepidoptera

The external morphology of Lepidoptera is the physiological structure of the bodies of insects belonging to the order Lepidoptera, also known as butterflies and moths. Lepidoptera are distinguished from other orders by the presence of scales on the external parts of the body and appendages, especially the wings. Butterflies and moths vary in size from microlepidoptera only a few millimetres long, to a wingspan of many inches such as the Atlas moth. Comprising over 160,000 described species, the Lepidoptera possess variations of the basic body structure which has evolved to gain advantages in adaptation and distribution.

Insect morphology

Insect morphology is the study and description of the physical form of insects. The terminology used to describe insects is similar to that used for other arthropods due to their shared evolutionary history. Three physical features separate insects from other arthropods: they have a body divided into three regions, have three pairs of legs, and mouthparts located outside of the head capsule. It is this position of the mouthparts which divides them from their closest relatives, the non-insect hexapods, which includes Protura, Diplura, and Collembola.

<i>Pseudobiceros bedfordi</i>

Pseudobiceros bedfordi, is a species of flatworm in the family Pseudocerotidae.

Maritigrella crozierae, the tiger flatworm, is a species of marine polyclad flatworm in the family Euryleptidae. It is found on the eastern coasts of North America and the Caribbean Sea where it feeds on colonial sea squirts.

Carpet flatworm

The carpet flatworm is a polyclad flatworm in the family Pseudocerotidae.

Pseudoceros canadensis is a species of free-living, flatworm in the genus Pseudoceros, belonging to the family Pseudocerotidae.


  1. Hyman, Libbie H. (1959). "A further study of micronesian Polyclad flatworms". Proceedings of the United States National Museum. 108: 543–597. Retrieved 12 April 2020.
  2. 1 2 Robert Dinwiddie (2014). Ocean: The Definitive Visual Guide. Dorling Kindersley. p. 272. ISBN   9781465436207.
  3. Wei-Ban Jie; Shih-Chieh Kuo; Hin-Kiu Mok (December 2014). "Re-description of Thysanozoon nigropapillosum (Polycladia: Pseudocerotidae) From The South China Sea, With Observations on a Novel Pre-Copulatory Structure, Sexual Behavior and Diet" (PDF). Raffles Bulletin of Zoology. 62: 764–770. Archived from the original (PDF) on 2015-12-11.
  4. Robert Dinwiddie (2014). Ocean: The Definitive Visual Guide. DK Publishing. p. 272. ISBN   978-1-4654-3620-7 . Retrieved 2018-07-12.
  5. Jie, Wei-Ban; Kuo, Shih-Chieh; Mok, Hin-Kiu (2014). "Re-description of Thysanozoon nigropapillosum (Polycladida: Pseudocerotidae) from the South China Sea, with observations on a novel pre-copulatory structure, sexual behaviour and diet" (PDF). The Raffles Bulletin of Zoology. 62: 764–770.