Reproductive Biology of The Solitary Ascidian, Herdmania momus (Ascidiacea: Hemichordta) from Hurghada Coasts, Red Sea, Egypt

El-Sayed M,Hanafy H,Gad El-Karemm F,El-Damhogy A

doi:10.21608/eajbsz.2018.13429

Abstract

The reproductive biology of the ascidian Herdmania momus (Savigny, 1816) was studied at anthropogenic impacted sites along Hurghada coasts, Red Sea, Egypt, during January - December 2013. The specimens of this species were collected monthly from the shallow subtidal zones, and varied from 1.20 to 7.0 cm in total length and from 1.28 to 50 g in total body weight. The results showed that, H. momus is hermaphrodite, carries ovaries and testes at the same individuals, but ovaries are larger in size and shapes than testes. The smallest immature individual has 1.2 cm in length; while the smallest mature individual measured 1.46 cm in length and 1.18 g in weight, with ovaries of 0.041g in weight. The sexually mature individuals of this species have ovaries containing oocytes varied in shapes and sizes, passing through four main stages of maturation reaching stage IV or late vitellogenic stage (ripe ova), with oocytes varied from 100 to 140 µm in diameter, characterized with deep orange color and dense accumulation of yolk granules. It was followed by stage V or spent stage of irregular resorbed eggs. The appearance of ripe ova at stage IV showed spatial and temporal variations. The monthly averages of gonadosomatic indices (GSI) exhibited that, the whole populations of this species at all sites have lengthy breeding season extends nearly all the year around and characterizes with high peaks in gonadal activity during January (6.21), April (6.15), June (6.47), July (6.28), declined slightly in May (5.86), and September (5.15), with remarkably spatial variations at the studied sites. The number of mature eggs or fecundity varied from 1481 to 3724 and averaged of 3082.96±769.96 eggs for all populations. These values exhibited greatly individual variations denoting to partially spawning for each individual. The relationship between total body length (cm) and mean the number of eggs (fecundity) showed an increase in egg number with an increase in animal length

Highlights

Ascidians or “sea squirts” are a group of soft-bodied marine animals belong to Class Ascidiacea, Subphylum Tunicata, within Phylum UrochordataEl-Sayed, A
Testes are being attached to the ovary side, while gut loop beings enclose the left gonad at the posterior end
Ovaries are varied according to maturity stages from thread-like at the early stage to lobulated long structure at late stages and in all are longer than testes

Summary

Introduction

Ascidians or “sea squirts” are a group of soft-bodied marine animals belong to Class Ascidiacea, Subphylum Tunicata, within Phylum UrochordataEl-Sayed, A. Ascidians or “sea squirts” are a group of soft-bodied marine animals belong to Class Ascidiacea, Subphylum Tunicata, within Phylum Urochordata. (Millar, 1970; Vine, 1986; Shenkar, 2012) These are the largest and most diverse class of the sub-phylum Tunicata comprises approximately 3000 described species found in all marine habitats from shallow water downwards to deep water environments (Millar, 1970). Adult ascidians are sessile, inhabiting a wide variety of hard habitats mainly coral reefs and rocky substrates, as well are successfully foul various artificial hard surfaces and natural substrates such as rocks, eelgrass blades, pilings, shells of bivalve mollusks, jetties, ship and boat hulls, floating docks and other man-made structures all over the world to the deep sea (Millar, 1970, 1971; Vine, 1986; Shenkar, 2008, 2012). On the other hand, grow in thick, slimy mats that can range from dime-sized to huge colonies as large as sheets of plywood ascidians (Shenkar, et al 2012)

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