Since hissing cockroaches are insects, they’re by definition invertebrates. It’s a little confusing considering that the word vertebrate would suggest that they have a strong back and it’s obvious that roaches have a pretty tough shell on the outside of their bodies, but vertebrates have an actual spine according to scientists.
Most of the biologists I’ve found argue that the tough exoskeleton found on many insects, including roaches, are wholly external and therefore aren’t considered an actual backbone. That doesn’t mean they’re weak by any means, however.
Hissing cockroaches might be considered invertebrates, but that outside skeletal covering can actually withstand a fair amount of force. In many ways, it’s actually stronger than a vertebrate’s backbone for the size.
If you’re a little confused at the exact division between vertebrates and invertebrates like I was, then you might just want to ask yourself if a particular animal has a genuine spine. Those that don’t are always invertebrates.
Definition of a Vertebrate
While scientists like to argue about nearly every topic, it seems that they generally agree that vertebrates are all species of animals that have a stiff rod running through their bodies. This normally takes the form of a vertebral column, which manifests itself as a spine or backbone.
By this definition, you’re a vertebrate! If you have a pet dog or cat, then they’re a vertebrate too because they have a clear spinal column.
Judging by the sources I’ve read, all vertebrates have their mouth positioned around the front side of their bodies. This isn’t always the case with invertebrates like hissing cockroaches and other insects.
Definition of an Invertebrate
While it might sound a little silly, invertebrates are simply animals that don’t meet the criteria to be considered a vertebrate. They don’t have a defined vertebral column and completely lack a spine or other sort of backbone.
In the case of hissing cockroaches, they don’t really have bones at all and instead have an external exoskeleton shell that takes the place of bones. Hissing cockroaches are invertebrates as are all other insects.
Since this definition is really broad, I’ve found that scientists consider everything from snails to earthworms to be invertebrates. This category even includes some creatures, like coral, that you might not normally think of as animals even though they are!
Differences Between a Hissing Cockroach and Common Cockroaches
While the most notable feature of a hissing cockroach is its ability to produce a characteristic noise that’s given these creatures their unusual name, there are also a number of other aspects that have helped to set them apart from other members of the roach family:
- Hissing cockroaches are flightless and normally lack wings
- They possess relatively openings called spiracles, which are in their abdomen
- They’re only found in and around Madagascar natively, while most other roaches have colonies all over the globe
- Most cockroaches adapt to many different environments, but hissing cockroaches generally live in wooded areas
- They’re generally much wider than other species
- Males have horny bumps behind their heads, which is unusual for roaches
- Adults boast a brown color gradient along their backs, while most roaches are a single shade of brown
- Their antenna tend to be long and straight, as opposed to the curved feelers of other species
- Adult hissing cockroaches can grow to two inches long
- All hissing roaches can shimmy up sheer surfaces better than other roaches can
How can You Tell if a Hissing Cockroach is Male or Female?
A number of pet experts I’ve come into contact with have pointed out that male hissing roaches will always have a pair of large bumps that protrude out from an area right behind their head. It’s a little hard to see it at first, but once you know how to spot it you’ll easily be able to tell males from females.
The horn-like protrusions are normally found on a roach’s pronotum, which is a sort of jointed section of hard tissue that’s right behind the head. Mature male roaches will actually use these bumps to fight other males in a show of dominance sort of like how deer or sheep might.
If one hissing cockroach is showing signs of aggression toward another, then there’s a good chance that it’s a male. Adult female hissing roaches aren’t aggressive toward others, which is why they don’t have the horn-like shapes behind their heads.
Take a look at their antennae as well. Females tend to have smoother fibers while males will normally have rougher ones.
Species of Hissing Cockroaches
According to most taxonomic texts I’ve seen, there are 20 different species that belong to the so-called Gromphadorhini tribe of hissing cockroaches. That being said, most of these really aren’t that different from one another.
The main groups are:
- Portentosa – Particularly large-sized hissing cockroaches that are quite popular as exotic pets; known generically as the Madagascar hissing roach
- Elliptorhina – A genus comprising ten different species that are found on Madagascar and a nearby island in the Indian Ocean
- Oblongonota – Often called wide-horned hissers in the pet trade, in part due to the prominent protrusions found on the backs of adult males
- Gromphadorhina – Technically a large family that includes both the Portentosa and Oblongonota roaches, this group’s name is often interchangeable with the term hissing cockroach in general
- Picea – Very similar to oblongonota roaches, which has caused them to be confused by some pet dealers
- Princisia – Smaller than most others in the family, though still much larger than most cockroaches in general
- Aeluropoda – This species comprises the flat horn hisser family, whose males have considerably flatter thoraxes than most of the other members of the hissing cockroach tribe