article: It may not be a looker, but the Lusitanian toadfish can do much more than croak. The fish, which lives in rocky crevices in the Mediterranean Sea and Atlantic Ocean and glides over the muddy sea floor, can whistle, croak and grunt. Scientists have found that Halobatrachus didactylus makes five types of calls not only to attract a mate, but to warn off rivals too may be trying to swipe their nesting site. Lusitanian toadfish (pictured) make five types of calls and males can even sing in choruses to attract mates. The fish woo females with long, rhythmical boatwhistles, which also act as a deterrent to love rivals, . Male fish woo females with long, rhythmical noises that sound like boat whistles, which also act as a deterrent to love rivals, New Scientist reported. They build nests under rocks during mating season, which runs from May to July and sing to attract female visitors. If they are successful, the pair mate and the male looks after young that hatch from sticky eggs until they are ready to fend for themselves after around a month. Because males, which grow up to 20 inches (50cm) long, are fiercely territorial, their song also serves as a warning for rivals to stay away. Males build nests under rocks during mating season (pictured), which runs from May to July and sing to attract female visitors. The creature is well camouflaged so sound is the best way to get attention . This is important because males nest close together to one another and form singing choruses like frogs or toads to demonstrate their virility and strength. The whistles vary according to the size of the fish, meaning that specific calls from larger specimens are particularly effective at deterring another fish from picking a fight and stealing a nest. Lusitanian toadfish typically weigh more than four lbs (2kg) and their large, flat heads and wide mouths, make them look like toads, giving their their name. Portuguese scientists discovered that the sounds made by Lusitanian toadfish indicate who they are, their motivation and information about their nest. If they are successful, the pair mate and the male looks after young that hatch from sticky eggs until they are ready to fend for themselves after around a month. Here, a female lays eggs, which stick to the roof of a nest . The experts analysed the frequencies of different songs.  Water temperature, tide level, fish motivation and the level of social interactions affected most acoustic parameters analysed (shown above). For example, during low tide, the sounds made by the fish were shorter in duration and had lower main frequencies . Male mice sing to woo females, scientists claim. They also change their tune depending on whether she is within sight or not. The females, meanwhile, seem to like some of the songs more than others. In a quirky study that could shed help shed light on autism and other conditions that involve difficulties in communication, researchers from Duke University in North Carolina studied male mice that were either placed in a cage with a female – or one with just her scent. Special equipment was used to record and analyse their squeaks, which are so high-pitched that people can’t hear them. This revealed that they sang one song when they could simply smell a female and another one when they could see her. When they could merely smell a potential mate, they belted out an extremely shrill and complex song, perhaps in an attempt to make themselves known. But when she was within sight, they serenaded her more softly. These songs also had a more simple structure and were longer. Clara Amorim of ISPA University Institute in Portugal studied the different sounds made by the fish, which contracts muscles in its swim bladders to release air, a little like bagpipe. It makes different sounds by contracting its bladders in various ways. To prove that 'boatwhistles' are used as a deterrent as well as for seduction, her team deflated the swim bladders of fish under anaesthesia, so that the creatures could still contract their muscles, but were rendered silent. The team found that mute males were more likely to face intruders in their nests, suggesting that 'boatwhistles' are an effective warning siren. ‘Boatwhistles are a cheap way to exclude intruders without engaging in a fight,’ Dr Amorim said. ‘Seeing that a nest is occupied is not as effective as hearing that there is a male in the nest eager to defend its territory.’ The sounds are modified by environmental factors such as tide level and water temperature as well as courtship motivation and by social interactions. For example, during low tide, the water temperature rises slightly and it's harder for sound to travel in shallow waters, which means that fewer fish sing and their noises are shorter in length and lower in pitch. They found that males that are desperate to mate sing a lot more at higher frequencies with longer notes. Males singing as part of a chorus sing more than they do when they are alone. Fish that sing the most, were found to be capable of a contracting their sound-producing muscles more and therefore showed that their body is in good condition. This means that males that can sing for longer have more energy reserves to defend the nest and to care for the eggs, and could enjoy higher social status and reproductive success as a result. Other fish sing too, such as clownfish, which click their jaws together to scare off intruders. Male Lusitanian toadfish build nests under rocks during mating season, which runs from May to July and sing to attract female visitors. Other fish sing too, such as clownfish (pictured), which click their jaws together to scare off intruders .
highlights: Lusitanian toadfish lives in the Mediterranean Sea and Atlantic Ocean .
  Attracts mates by singing various songs, which also warn off rivals .
  Songs tell others how large the fish is and how strong and healthy it is .
prediction: the Lusitanian 
   can 
   croak 
   in the Mediterranean Sea and Atlantic Ocean and 
   whistle 
   Scientists 
   didactylus makes 
   mate 
   warn 
   make five types of calls and males can even sing in choruses to attract mates 
   The fish 
   . 
   fish woo females with long, rhythmical noises that sound like boat whistles, which also act as a deterrent to love rivals, 
   They build nests under rocks during mating season 
   from May 
   July 
   female visitors 
   they are 
   warning for 
   their their 
   of a nest . 
  