Polycarpa sp.

POLYCARPA

Genus Polycarpa includes a long line of what is commonly referred to as: sea squirts or tunicates. They are hard shell like structures, with the body covering being made of a compound called tunic. Interestingly enough, the tunic is made of cellulose(glucose)! This is where their other name “tunicate” comes from. They attach to a fixed object with siphons protruding from all over its body. They are considered to be filter feeders, taking their food in through their siphons and straining through a mucus sheet within the body cavity where the water is then expelled on the other side.

They can not be exposed to air as this will interrupt their filtration system and instead fill it with oxygen, which is detrimental to these filter feeders.

Caring for thriving colonies of Polycarpa is often viewed as the pinnacle of reef keeping. These require a stable tank with daily feeding(with things like phytoplankton, copepods, calanus etc). Successful tunicate husbandry is highly rewarding as these animals are known for being difficult to keep. There are over 204 species in this genus and they come in many different colourations and growth formations.

WATER CHEMISTRY

Polycarpa should be kept in a mature reef aquarium that has stable water parameters and daily feeding. While we have our preferred parameters for Alkalinity, Phosphate, and Nitrate, Polycarpa will do far better in your system if you just focus on keeping the water chemistry stable. If your Alkalinity, Phosphate, or Nitrate is out of line, our recommendation is to get it back to your target levels as slowly as possible. 

We also highly recommend daily feedings. This may cause an inflation in your nitrates and phosphates depending on what foods you are feeding your tank. Live phytoplankton typically is your best choice as they do not spike your nutrients, some even decrease them!

The parameters we aim for are:

It's important to understand that these are the levels that we aim for in our SPS system. However, that doesn't mean they are the right levels for your system. All aquariums are different and your system may naturally fall on a different balance. You're better off working with the balance your system tends towards than trying to force the same levels that we run.

FLOW

In terms of flow, Polycarpa should be getting a high amount. As they feed through filtration it is important that they are placed in an area with high flow. This is so that they can filter the food through their systems to ensure their survival. 

With too little flow you will find that your tunicates siphons will close and it will start to tur a darker colour indicating that it is not having its needs met in terms of flow.

LIGHTING

Lighting is not important to Polycarpa, as again they do depend on food in the water column to survive as opposed to photosynthesis like coral.