Episode 327 – Crab Hacker Barnacle: Master of Puppets

“…and today we’re talking about an animal hacker of animals. But more on that later.”

They say the best defense is a good offense. But they rarely say the opposite. Crabs are little armored warriors scuttling around on the ocean floor, but even their rigid carapace isn’t immune to a little subterfuge. Enter the crab hacker barnacle. A sinister little worm that sets up shop and gets to work turning nature’s armored ocean bugs into their own personal breeding grounds. But when you’re a small barnacle in a big ocean, you have to use what you can to survive here in Life, Death, and Taxonomy.

Description of the Crab Hacker Barnacle

  • Sexual dimorphism: Individual barnacles differ significantly between males and females.
  • Female barnacles resemble small slugs early in their life cycle.
  • They develop nutrient-absorbing tendrils and grow over time.
  • In contrast, male barnacles are much smaller and primarily assist in reproduction.

Life Stages:

  • Virgin Externae: Colorless, lasting approximately two weeks.
  • Immature Externae: Milky-white or yellowish, lasting four to six weeks.
  • Sexually Mature Adults: Purple, brown, or dark brown.
  • Senescent Externae: Wrinkled and blackish, similar in size to adults.

Measure Up

Welcome to the beloved Measure Up segment. The official listener’s favorite part of the show! The part of the show when we present the animal’s size and dimension in relatable terms through a quiz that’s fun for the whole family. It’s also the part of the show that’s introduced by you when you send in audio of yourself saying, singing, or chittering the words Measure Up into ldtaxonomy at gmail dot com. We don’t have a new Measure Up intro!

Creature Culture: The ugly barnacle 0:09

Adult size

  • 11–22 mm (0.8 inches) wide
  • How many hacker crab adults go into the diameter of a Crunchwrap Supreme?
  • Hint: A Crunchwrap Supreme is a large flour tortilla that is wrapped around ground beef, taco seasoning, nacho cheese sauce, sour cream, and a hard flat taco shell. It’s wrapped into a stop sign shape. 
  • 8.75 barnacles. The Crunchwrap is seven inches in diameter.

Larvae size

  • 2-5 mm (0.19 inches)
  • How many barnacle larvae go into the width of Monaco at its widest?
  • Hint: As a tiny chip off of France, Monaco is the second smallest country in the world after the Vatican. It also has the shortest coastline in the world.
  • 352,231.5 barnacles. The width of Monaco at its thickest is 81,700 meters (5,577 feet).

Fast Facts about the Crab Hacker Barnacle

Habitat and Distribution: Preferred habitats for its host crabs include coastal waters with mud, rock, or sand substrates. In the larval stage, they are adrift in open water. They tend to stick to coastal waters, where their prey live. You might be able to find them in the waters of North and South America, southern Africa, and Australia. 

Diet: Hacker crabs are parasitic, along with all the members of its family. It primarily target free swimming crab species, including the green crab.

Major Fact: Master of Puppets

  • Most barnacles just latch onto rocks, boats, and other hard surfaces to use filter feeding
  • They even do commensalism when they latch onto large animals like whales
  • But the crab hacker has a different strategy, and this one is more sinister
  • The life cycle of a crab hacker is one out of a nightmare by HR Geiger – combining body horror, mind control, parasitism, and reproduction.
  • It starts with a female larval crab hacker as it crawls along the carapace of a crab – most likely, a green crab
  • It stops when it reaches a spot to settle on and then grows into its next stage – the kentrogon
  • Once it’s a kentrogon, it develops a kind of tiny spear that it uses to pry its way into the crab’s shell
  • When it’s in the safety of the crab’s shell, it will grow into two parts: the interna and the externa
  • The externa is a large yellowish mushy sac that is pushed out of the crab’s carapace
  • The interna, however, starts growing tendrils that spread throughout the crab’s internal organs
    • This allows the crab hacker to absorb nutrients from its host’s digestive system and also tap into its nervous system, letting it actually control the behavior of the crab
  • It’s important to note that, like a good parasite, it doesn’t kill or maim the host, though it does make it harder for the crab to survive. Instead, it basically takes over its reproductive system.
  • If a female crab is infected, she will lose her ovaries in favor of the externa sac that contains the barnacle’s eggs instead. Since her eggs would have been carried in the same place, it’s no difference to the crab.
  • For male crabs, their gonads are atrophied, making them sterile. But since their abdomen is widened to make room for the externa parasite egg sac, they actually undergo a sex change and develop ovarian tissue.
  • But all this sick mayhem is caused by the female barnacle. Male crab hacker larvae swim around until they come into contact with an externa sac, then they worm their way in through small pores and fertilize the tens of thousands of eggs kept there.
  • Once the eggs are fertilized, the barnacle drives its decapodian jager onto a rock, have it bob around to release the eggs, and then push them into the water.
  • Another side effect of this is that the crab can no longer molt when it gets infected. So it can’t get bigger.
    • This affects humans eating them since not only does the parasite make them infertile and control their population, but it also makes it so that small crabs will stay too small to eat
    • Plus, not being able to molt means not being able to regrow limbs, so the crab has a decreased change of survival unless the power ranger is good at driving this thing 

Ending: So find a new best friend, worm your way into their heart, and use them like an anime giant robot like the crab hacker barnacle here in LDT.