TITLE: 8. Taxon Group: Echinodermata
AUTHORS: Kesella Scott-Somme, Chris Fletcher, Inez Januszczak

[DESCRIPTION]
This is part of the collection "DToL Taxon-specific Standard Operating Procedures (SOPs) for Marine Metazoa", lead by the Other Metazoa Working Group. The SOP collection contains guidance on how to process the various marine Metazoa species within the scope of the Darwin Tree of Life project. The guidance specifically refers to the tissue samples needed for DNA barcoding (which takes place at the Natural History Museum (NHM) and at the Marine Biological Association (MBA))  and outlines the dissected tissues required for whole genome sequencing, which takes place at the Wellcome Sanger Institute. Every specimen is submitted for DNA barcoding first before potentially being sent to the Wellcome Sanger Institute.

Definition: Within Echinodermata adults are recognisable by their (usually five-point) radial symmetry and include starfish (Asteroidea), brittle stars (Ophiuroidea), sea urchins (Echinoidea), sand dollars (Clypeasteroida) and sea cucumbers (Holothuroidea), as well as the sea lilies or "stone lilies" (Crinoidea).

Including: Aforementioned Asteroidea, Ophiuroidea, Echinoidea, Clypeasteroida, Holothuroidea and Crinoidea.

Excluding: Species smaller than 5mm. 

See the Guidelines for important details and checklists.

[GUIDELINES]
Field sampling:

1. Environment to be sampled: Marine 

2. Trap/method of sampling: individual collection by hand, intertidally or by diving. Also capture by ship-towed gear (dredge/trawl etc.) possible. 

Do not collect more than necessary.

 

For genome sequencing:

3. Specimens can be sampled and frozen whilst still alive. 

Narcotisation prior to dissection should be considered as a humane precaution, to dislodge associated organisms, and (ophiuroids) to prevent autotomy of arms.  Propylene phenoxetol (0.1% in seawater), or Magnesium chloride (isotonic solution mixed 50:50 with seawater) or menthol crystals (allowed to dissolve in lidded specimen container) can be used. 

Photography:

4. For UK species: 

Oral and aboral views of whole specimen plus the Spicules if collected for ID. 

 

5. The image should be taken in the highest quality resolution - a macro lens is recommended.  The photos should be of high enough resolution to be diagnostic, when possible.  

Photograph to include a unique identifier (e.g. QR code, specimen barcode) where possible; when no voucher specimen parts are retained the photograph will serve as voucher and should include identifying features. 

 

Dissection for DNA barcoding:

6. The following tissues have been used as sources of DNA for DNA barcoding and whole genome if required. 

 

Once the tissue for barcoding is removed, that tissue should be placed in 100% ethanol. The rest of the frozen/live organism can then be dissected.  

Dissection for whole genome sequencing

7. Many echinoderms have less tissue due to the presence of spicules (sharp pointed structures), and so dissecting out 5mm sized sections may be challenging. 

Each sample must be frozen with minimum delay at -80°C or colder.

 

Storage of frozen tissue:

8. If barcoded tissue passes the DNA barcoding stage, subsequent frozen tissue of specimen to be sent to Wellcome Sanger Institute. 

 

9. Leftover tissue from specimens must be sent to NHM for vouchering and long term storage.

Storage of voucher:

10. Vouchers to be sent to and kept at NHM.

Regarding tissues to retain for the voucher specimen; for relevant species species the mouth and arms are needed for identification. Keeping one arm attached to oral disk and taking other arms for sequencing is the easiest and quickest way to process. For Echinoidea the mouth with a section of the test should be sufficient. 

Photo guide: Asteroidea (starfish)

 
Photo guide: Echinoidea (urchins)

  


[STEPS]