Whether it’s on a rain-soaked sidewalk, in a compost bin, or on the end of a fishhook, most people are familiar with the segmented worm. But what about all the other worms out there?

There are more than 1,000 species of tapeworms (Phylum Nemertea), most of which are found in the ocean, and the different species vary in size and lifestyle. A distinctive feature of tapeworms is the proboscis – a unique muscular structure in the worm’s body. To attack prey, they squeeze their bodies like the fingers of a latex glove to push out their proboscis.

ribbon worm proboscis

The largest species of tapeworm is the laceworm Lineus longissimus, which wriggles between rocks in North Sea waters. Not only is it the largest nematode, it may also be the longest in the world! Uncertainty remains, as these stretchy worms are difficult to measure accurately, but they are more than 30 meters (98 feet) long and are believed to even grow to 60 meters (197 feet) – longer than a blue whale! Despite their length, they are less than an inch tall.

The smallest species of tapeworm, less than an inch long, is more like a thread than a worm we think.

Tapeworms possess highly developed muscles that allow them to contract their bodies, shrinking to one-tenth of their extended length when threatened. Speaking of stretching, tapeworm muscles don’t just contract – they stretch, allowing some species to swallow prey twice their slender width (like other types of worms, fish, crustaceans, snails and mussels )Body

The proboscis varies from species to species. Some are sticky or have suckers to grab prey, and some species, like those of Hoplonemertea, even stick prey on their proboscis with sharp spines called stylets.

Since stilettos are often lost in raids, worms are constantly crafting and using replacements they stockpile in their inner pouch.

As a second line of defense, many tapeworms are poisonous and taste bad. Several species of puffer fish contain tetrodotoxin, the notorious tetrodotoxin that causes paralysis and death by suffocation. It’s unclear how the toxins are produced — they may be left behind in the worm by ingested bacteria — but they could deter predators from taking a bite. Some even excrete toxins from their proboscises.